4th Dec 2011:
Begun writing this guide

In this guide I am to show you:

The OP Volibear
How to play him RIGHT
How to use his skills properly (some people don't know how to, guess it's because he's new)
What NOT to do.
The Nut and bolts of Volibear.

This is my first guide, so don't criticize me until you have read and actually use this build correctly. Buying the gear and playing Volibear you own way and failing does not mean it was MY fault.

For those who like to read about champions, here it is:

"Though the northern reaches of Freljord are some of the most unforgiving lands in Valoran, the Ursine have survived upon the region's barren, stormy tundra for centuries. As a fierce and respected warrior of the Ursine, Volibear devoted his life to the protection of his people and loyalty to his elder brother, the tribe's chief. When his brother was killed during a hunt on the tundra, the tribe looked to Volibear as his successor. It was an honor and a burden that Volibear had never expected, but he shouldered the charge with pride. However, by Ursine tradition, the tribe could not recognize Volibear as chief until he returned from a journey to the peak of their sacred mountain, a place forever shrouded in a thundering maelstrom. There, Ursine chieftains must speak to the storm itself, gaining clarity and wisdom to empower them as mighty leaders.

Donning the chieftain's traditional armor and enchanted gauntlets, Volibear began the long and perilous climb up the slopes of the mountain. When he reached the peak and gazed into the raging storm above, he saw a horrific vision of a Freljord utterly consumed by war. Amidst the carnage, the Ursine fell dead upon a bloody battlefield. Believing the vision to be an omen of things to come if he did not act against them, Volibear traveled to the capitol of Freljord. The Ursine had not ventured across the southern mountains in centuries and his appearance was met with unease. However, Queen Ashe recognized Volibear as a wise and powerful ally. In what Volibear considered the first step against a war-torn future, they forged an alliance. As part of their agreement, he joined the League of Legends in the name of a unified Freljord, representing the primal might of his nation on the Field of Justice."

Pros:

GREAT early game, Mid game, Late Game ( IF played right and timed)
Massive tank, equal to that of Garen in term of HP
Does massive damage with Frenzy
A very good chaser with core
He's a polar bear <3

Cons:

May have trouble building his gear due to "LUCK" as he may not be fed or given opportunities to farm.
Gets payed out for playing as he is OP and requires no skills apparently.

Greater Mark of Desolation is used because it offers Good Damage boost early game and allows Volibear to rip through first blood.
Greater Seal of Armor this is used to reduce damage in the instance of first flood fights and hence allows you time to build up Frenzy and get your opponent to approx 20% HP and killing with Frenzy
Greater Glyph of Scaling Magic Resist is used for tanking AP champs late game.
Greater Quintessence of Health is for the extra HP in lane, paired up with Ruby Crystal, give an additional 256HP. Thus fulfilling your role as a tank.

You can sub Greater Quintessence of Health with Greater Quintessence of Movement Speed for added chasing ability, but I prefer HP Quints as it allows for sustainability in lane and added bonus to Frenzy

I choose 0 21 9, as I believe that Volibear should fulfil his role as a tank, the 9 in the Utility tree is mainly for the added time of buffs.

I get this item first because it adds great bonus for Frenzy and also the added HP and allows you to be one step closer to building Warmog's Armor. This item also allows for you tank more damage and thus allowing you the chance to get First Blood. And if you think it's a bad item, because it doesn't have armour or HP regen like Doran's Shield, your right AND wrong, I DID choose . The combination of Ruby Crystal and Heal allows for a better chance of First Blood.

I rush this item first so that Volibear can tank earlier and receive that bonus for Frenzy . This item for me is essential for Volibear.

This item is very good for tanks as it give tenacity and M.Resist. If your up against a AD orientated team then go for Boots of Swiftness. It helps you chase chase down the Enemy with and thus slowing them with or Sky Splitter.

ALWAYS get Giant's Belt first. This is so further add to his tankiness and Damage for Frenzy . Although Frozen Mallet could be purchased after Atma's Impaler. Anyways I get ] for the added CC that Volibear posses and it also ensure that you can keep an enemy close enough to you to kill him with . In addition it gives your team time to catch up and Lay Waste to the poor soul.

With a Frozen Mallet and Warmog's Armor it's a no brain-er that volibear should get Atma's Imapler, this is for a MASSIVE increase in Attack Damage and Armor. With this Ends the CORE

If you are up against a balanced team:

This is viable as it gives both Armor and M.Resist and protection against CC.

This is great for the team and especially for you as it allow for you to EASILY chase or run away. The bonus HP is nice.

Is a good item in terms of armor and M.resist, this item is a late game item for volibear, so it may be little use as it may not die, but in the unfortunate chase that you do, you resurrect and pop a Heal and run away.

is a maybe in my opinion as it does give HP and AP (which is not really needed) that boosts your Stormbringer Damage and ALSO slows your targets, this also applies with Sky Splitter. I'm reluctant to buy it, but it can help a bit.

If your up against a heavy AD DPS team:

Its a no brain-er if your up against , this will wreck them so hard, unless they have a lot of Life steal, but it great for armor and extra damage in terms of its Unique Passive.

A great item for Volibear if he's against an AD team, this not only gives armor, it gives HP and a slow on Attack speed.

Paired up with Randuin's Omen, Master Yi hits like my old granny. The mana is also very helpful as Volibear can run out of mana at times. + will give 200 ARMOR and a natural slow and reflection to boot.

Up against a heavy AP Team:

This item is one of the best M.Resist itmes and the bonus move speed is very handy too.

The bonus of magic resist appeals to me and as well as the bonus healing this items offers. After a nuke and your're below 30% The Relentless Storm will pop off and the bonus of visage will further increase your heal. I don't really get this item much because in my opinion it's not worth the space.
Other items I mentioned in the balanced team section are viable too.

This spell is now almost OP, combined with Summoner's Resolve it's amazing for tricking your enemies.

Scenario 1: First blood attempt
Enemy: "Kill Volibear He's almost down"
Pops heal and passive.
Enemy: "WTF?!"
Volibear has drawn firstblood

Heal is generally used to save allies and yourself after taking damage, never use it if you know you're gonna make it out alive with like 500-ish hp or just know your gonna get back to base without facing an enemy.

I use this to flash away or in and reck havoc with Sky Splitter and Stormbringer

This is another viable summoner spell and it heals you chase your enemy, I don't like in that it only used for ganks, it works well with Singed size 30 because it allows him to spread his poison and fling.

this if taken first and maxed first because Frenzy is essentially Garen's Demacian Justice. It's also used for first blood and early game kills.
When attempting first blood, attack the enemy that doesn't have flash and maybe ghost. You and your partner then decide who to kill, make sure that your partner has Exhaust as it is a great help. Keep hitting the enemy until he/she is around 20% health and Frenzy them and it's instant first blood. This involves a bit of co-ordination and luck. When ever you think you're ready toss your combo Attack attack and finally .

This is maxed second for the slow bonuses pretty much it. by slowing your opponent it just more time for your team to kill the enemies. Sky Splitter should also be used strategically early game, as minions tend to do quite a bit of damage, if you or your ally is being focused by minions and is fighting an enemy do a Sky Splitter and it'll give you guys precious time and health to kill your enemy.

I get this last because you really only need the fling effect. you can swap it with Sky Splitter but it only weaken your cc.

Whenever your in a massive team fight ALWAYS pop this baby up and cause some nice AOE damage, this will benefit your team and your gold count.

Comming Soon:............

Early Game:
Try to draw first blood, as it will give you a massive advantage. (see detail on Frenzy section)

Play passive until you have got 2 Frenzy 1 Thundering Smash and 1 Sky Splitter you can begin to start chipping away your enemy's HP until you can kill them with a combo of Thundering Smash --> Sky Splitter --> Hit Hit....--> Frenzy . This combo with the aid of your partner you will be able to consistently get kills and more gold.
Earlier I mentioned "LUCK" what I meant was the opportunities you may get to get kills and first blood attempts. If the enemy has a jungler then go BOT lane with a partner as solo will most likely not walk into a bush.

Mid Game:

I tend to keep farming until lvl 11. By this stage you can either keep farming or start ganking. When ganking, activate Thundering Smash and target the squishy or a target the team has agreed on. Once you have tossed the enemy immediately activate Sky Splitter this causes your enemy to slow and as well as surrounding enemies that maybe near by. Simultaneously pop Stormbringer so that whilst focusing one enemy you will be also damaging some surrounding enemies. One the enemy has reach 20% HP use Frenzy and hey presto a kill.
I tend to use Frenzy on a tank as it is more effect and better for tanks as Frenzy is pretty much an anti tank skill. Like my RPG.

Late Game:

Hopefully by now you have build your core and filled in the games. During this stage you will really shine. with over 4.5kHP and good armor all you do is walking in the middle of a fight cause some damage can tank so much damage its not funny. In the middle of a fight keep an eye on your team's HP and pop a Heal if need be.

Notes: If their carry is focussing your squishes then fling them with Thundering Smash this will somewhat cause confusion and cause the enemy carry to just attack a random (hopefully you).

GLHF

I will add more stuff has I get more time. Post comment of what I can add.