I guess I figured I'd make a built because many people are curious about jungling on Alistar since his most recent remake. Yes jungling works and yes it's fast and yes it's amazing. You don't have to follow this guide word for word but it's what I've found that works and does pretty decently.

Start at wraith camp, smite the large one the second it spawns then instantly Q, kill the camp and loose less than a bar of hp. Head to wolfs, auto attack once on the large one then Q (this lets you get 1 free auto attack in without taking damage after it). Once big is dead get your heal then cast it to help finish off the smaller onces, cast it once more the second it's ready (usually right after you finish the camp off) head to blue and do the auto attack Q thing again and kill blue buff with ease, throw a point into W and head over to small golems. Open with W then wait for your passive buff to wear off then press Q, wait... then E, etc. Head to red take it out pretty easily as well. Remember to health potion throughout the jungle.

The most important part of ganking is to know what you can do as Alistar, know your damage sucks and know how to position yourself. Simply make sure your teammate(s) know(s) you are about to gank by clicking AND saying in chat. Try as hard as you can to come in from behind the enemy and open with W to knock them into your teammate(s), then cast Q, wait 3 secs and cast E, should be pretty simple. Also knocking them into your turret is wise... (duh).

I wouldn't focus too much on counter jungling as much as ganking unless you have no gank opportunities, it's just that Alistar isn't too amazing in the jungle compared to some other champs such as Warwick and Udyr.

Runes are up to you however the ones I use work very well. You could go magic pen red/ mana regeneration yellow/ cooldown reduction blue/ Hp quints or something else or a mix... whatever.

Skilling... I focus on W first because early game single target damage is best to focus on and that is your highest damage ability to single targets plus being able to cast it once then Q then cast it again is fantastic. Focus on Q second because by then you are team fighting a bit, and E is just sucky =P.

Summoner spells... Smite is required and either ghost or flash are non-negotiable because you NEED them for maneuverability and positioning.

These are really all up to you I do what is seen but you can do really whatever you want and/or whatever the certain game calls for.

I build my cloth armor into madred's to help with jungling and get heart of gold to help with the lack of HP as well as giving him some awesome gold per 5, but I end up selling both items late game. Chose the defensive items and AP items for a very obvious reason... that is to get max mana while some defense to maximize archangel's staff. Banshee veil is nice for... well its the most Op item in the game, frozen heart gives armor, mana, CDR as well as a nice aoe debuff. Archangels gives much needed mana regeneration, force of nature is amazing for speed and magic resist but if you choose to get a sheen early game switch force of nature to lich bane late game, and rabadons gives some boost to your already present ap from archangel's so that your skills actually do something more than stun.