Honestly, jungle Alistar is amazing. Godly ganks, incredible sustain; it's just too good. Mana can be a problem without blue early on, but it's still amazing. Probably my favorite current jungler as of now. Had a game earlier with him, and it was absolutely hilarious; we had Yorick top, Akali mid, Sona AND Leona bot, and my Alistar jungle. Pretty much facerolled them, since we got Yorick and Akali fed to hell. Hilarity ensued.
Oh, and as a random note: if your jungler is a tank, please understand that it is up to you, the laner, to deal damage if you want the kill. I will bring the CC, you bring the pain. Yes, I can do damage as Rammus/Amumu/Alistar, but I'm not gonna take them from 100 to 0 before they can run away. I ping, I type my target in chat, so PLEASE follow me when I gank. And hey, sometimes I tower dive. If you can reasonably pick the enemy off, FOLLOW ME. You won't be taking tower damage, I will. I ward, we have vision, everyone else is accounted for, so we won't get randomly killed unless we're complete idiots. I just can't stand when people stand around derping because they couldn't right click/use an ability. Ugh.