!!!WARNING!!!Short but effective guide! ;)!!!WARNING!!!
Hello guys, thats my first guide and I hope it will be helpfull for you. First of all I want to start that I'm from Lithuania so my main language isn't english, that's why here will be a lot of writing mistakes. This build is made for people who don't like being squishy but likes huge damage output in short-mid time and rarely someone flees away from you because of Olafs legendary viking axe. Playing with this build I almost always dominate my lane just because of 1 thing - True damage which is huge and spammable. In teamfights other team dont focus you just because being realy tanky and it gives you advantage to catch enemy squishies and turn them off :D

Personaly I use:
9x Greater Mark of Disolation
9x Greater Seal of Vitality
9x Greater Glyph of Scaling Magic Resist
3x Greater Quintessence of Desolation
Well ArPen for your Q skill
HP for being beefy and spamming E + synergyzes with W

But you can swap Hp Seals for Armor seals if you lack armor early game
ArPen Quints for flat HP quints if you are going to spam you E a lot at the start of match

As you can see my task is to reach 40% CDR and be tanky, 40% CDR means that you can spam true damage every 2,4 seconds, which is 1360 true damage in less than 10 seconds and if target stays near you, you can spam your Axe without any cooldown because it comes up just after you throw it.

Doran's Shield - I haven't found better starting item as it lets you be tanky and stay in lane long, can be swaped with Boots and Health Potion but it is risky because you are melee champion and enemy can denie you from farming.
Frozen Heart - item which is my list number one, I love! Mana and CDR for spamming skills, Armor and Aspd reduction for survival.
Force of Nature - Very good item for this build as it gives you more speed, huge amount of MR and not bad HP regen.
Ionian Boots of Lucidity - Some people don't like these boots but I enjoy having it as there isn't any other good pick, you gonna say Mercury threads? Yeah but look at your ulti description and think again.
Warmog's Armor - Good amount of hp, synergyzes well with your W, BUT can be swapped with Frozen Mallet if you feel that you have enough HP but I don't feel like it would be usefull as we are going to spam our skills.
Youmuu's Ghostblade - Don't know what to say about it, epic item for olaf, 20 ArPen syngergyzes with your runes and ulti passive at lvl 16 with this item you will have 75 ArPen, like it? :D It also gives us CDR, this build is just about cdr and skill spamming, also active skill + your ulti in teamfight lets you to shut down atleast 2 squishy enemy carries.

If I reach late late game i usualy change my Doran's Shield for something situational, if I lack more armor I pick Atma's Impaler, if I lack MR - pick Banshee's Veil, if game is going well - pick something for better damage output.

I found Flash and Ignite to be most effective in my playstyle, but everything depends on you. All I can say that you dont need Exhaust because you have Undertow, but yeah, if you are newbie with olf or don't have skill in throwing axe you can pick Exhaust instead of Ignite, some people picks Ghost instead of Flash but Youmuu's Ghostblade active skill is enough to catch someone or run away, also Flash lets you to get out of the action when you are at danger zone like 200-300HP and lets you to flee away.

As you can see my point is to max my true damage because my enemy in lane feels it realy realy well and at level 9 I already have 340 true damage like every 3secs, also at this time i already have 1800+ hp while my enemy have just arround 1000-1200 and that let's me to win almost every laning phase. Every lane is different and enemy is different too, some lanes I lost, some I won, but all in all me and my partner won about 80% lanes. When we had soraka in enemy team at bot we had bad times, and you all know why :D

I usualy harass with my axe and if enemy is slowed and is near me I run to him, give him some true damage, pick my axe and throw it again, you have to be fast to do it, it's realy hard without practice, but when you learn it's possible to cut off 50% enemy hp just in 1 combo.
Always remember to turn on your W skill before throwing axes because it adds damage to your Q skill as it raises your AD.

I'm not going to talk about ulti as I think everyone knows how to use it.

Pros:
Beefy with good defensive stats
Have good slow
True damage every 2,4secs with 40% CDR and 60sec on ulti
Rarely focused because of being tanky
You are boss in teamfight because noone can stop you

Cons:
Your succes is depended on how good you mastered your Q throwing and timing
Sometimes bit boring :D
Requires good ulti timing

Well that was my first guide so don't blame me if I made writing mistakes or something other, I hope you gonna try it and give your results.

UPDATES:

2011-08-01:
Guide Created:
Runes added
Items added
Summoner Spells added
Skills added