This is the build I use when I either use Olaf as a jungle or as a solo top. He's quite tanky but can deal a decent amount a damage as well.

This build offers you an amazing amount of damage resistance along with a good amount of damage output which is rare in most off-tank/tank builds out there. And its not to expensive :D.

Flat Magic Resistance Glyphs: So AP's don't shred you to pieces and add to your overall tankyness.

Flat Armor Seals: Add to tankyness and help sheild from those AD carries.

Flat Damage Marks: To help your damage output early game and overall.

Flat Damage Quints: Deal good damage early and overall as well.

I use a 13/17/0. This is to be able to deal out some damage but at the same time be more tanky.

Start out with cloth armor and 5 pots to give you early on tankyness and lane or jungle sustain then boots next. Either if you are jungle or solo top build the razors then to a lantern to give you nice, cheep, early damage output and armor and it gives you a ward, so if solo topping you can ward yourself and if jungling you can ward your buffs or a lane for somebody. After that If your jungle get Treds next, or if solo top rush Phage for health and damage.(Solo top can get Treds after the Phage.) Then for jungle and solo top, pick up a Hexadrinker for magic resistance early on and nice damage. (The build now is for both lanes) Now your ready to build the top tier items. Purchase a Giants Belt for good sustain and build that into a Frozen mallet for its great health buff and slowing passive to keep your enemies in combat. Then depending on if you need more magic resist or AD resist based on the other team you either build into a Giants Belt to a Warmogs or build into a Mall of Mal or magic resist. (After you build one build the other right after) Then last pick up either a: Zekes Herald(For added health, attack speed, cooldown reduction, and life steal), Spirit Visage(For health, magic resistance, and added health regin adding to the Warmogs effect), or a Statikk Shiv(For what I'm hoping to give you some sort of health buf, attack speed buff, and I really hope its passive that allows a chain lightning effect.((I ogigionally had the Ionic Spark here but it is being removed))) [NOTE: Feel free to sell the Lantern when at full build to add something else if you so desire. Like an Atmas for armor and it will add around 56 dmg at level 18 because of its passive]

You want to build your Q 1st if you are solo topping for a good poke and harass. But if jungling build your W 1st for the lifesteal. If solo toping max your W 2nd and if jungle max your R. And all thats left is to max the remaining skills.

Solo top: Flash(or Tele)&Ignite. Jungle: Smite&(Flash or Ignite, depending on your play style or preferences).

FOR SEASON 3(since the popular spells are getting nerf'd). Solo top: Tele for sure & Heal,Ghost,or Exhaust. Jungle: Smite&(Heal or Ghost/Exhaust)(Heal for sustain and Ghost/Exhaust for ganks)

Pros

Naturally Tanky

Good Q harass for Solo and chasing because it slows.

Abilities attribute to a good lane sustain.

Cons

Low-ish damage output

Not as affective when abilities are on cooldown

Blues first for jungle sustain. Reds first for early ganking ability.

When farming use your basic attacks. And to take out large groups of creeps quickly if need be throw your axe in the middle of the mob to damage if not all but most of them. If low on health use your W to regin health while farming.

Your like a sort of off-tank/tank build so you are pretty good to dive in to a team fight and get your hands dirty. When chasing down some body use your throwing axe to slow them down.

I like my Olaf to be tanky because he has an awesome natural resistance to damage and his abilities help buff that. He is awesome for jungle because of his W and E to dispatch quickly of the monsters and he is awesome for solo top because of his natural tankyness and his Q is a great harass along with the lifesteal of his W.