Ironskins- in league with chaos dwarves. Lots of fancy weapons/armour that the dwarves make for them... EVIL! Lots of ironguts, leadbelchers and ironblasters
Lazarghs- ogres monks dedicated to the great maw. Many butchers
Goldtooth clan- Gresus's own. Love gold, rulers of all... but lack real character. Lots of ironguts and anything else you want to use (best fluff for mournfang heavy lists).
Eyebiters- used to be caravan guards (mercenaries) but now they are raiders. Grandfather Malron Eyebiter basically sired the whole clan... its one big family and he's the Godfather... just in ogre form. Used to be 'good' ish, now are described almost solely as raiders. Can pretty much take anything.
Mountaineaters- eat rock to make themselves hard, but living on the highest peaks is good fluff for hunters, stonehorn, thundertusks and mournfang.
Thunderguts- love guns in all shapes and sizes. Basically ogre gunlines with leadbelchers and ironblasters.
... there are many many more, but those are what I can vaguely remember off the top of my head. Its worth reading the entries that are given in the ogre army book, and if you can find it give a read to the old one too (less tribes, but gives more detail). There are lots of little random bits about many different tribes, but wihout caring about them in particular it just blends into one blob of "otehr tribes" in my head...