Diving (no more piranhas in Cyrodiil) - Argonians can't drown.
Brawling - Nords deal more hand to hand damage.
Parkour - Wood elves cost less stamina.
- OR - Diseases - Wood elves have resistances to diseases.
Drunk - Khajiit have resistance to skooma (and can enjoy its benefits without side-effects).
Recreational Magic - High Elves and Dark Elves have extra options.
??? - Orcs.
??? - Bretons.
??? - Redguards.
Any other ideas?