So far, I've got...
Wings: AoE attack for push/prone, or grant flight to ally (allies?).
Head: bite that saps healing surges, or breath attack that gives radiant vuln to enemies and temp hp to friends, effects on head transferred to body, can't be flanked, can only be attacked with CA.
Tail: slide/prone enemy, or slide ally
Claws: grab (automatic bite or squeeze on failed escape), or... ?
Body: terrain change, or transfer effect from ally to self, can slough effects to its other parts