Night elves — Shadowmeld Provides the hunter with a second aggro-dump (for when Feign Death is resisted. Also allows the hunter to enter a stealth state (which breaks on movement); can be very useful for surprising unsuspecting PvPers (especially with a Cat)
Tauren — War Stomp Causes a short area-of-effect stun around the hunter, useful for getting out of melee range.
Other racial attributes can also be useful, but may not be specifically relevant to hunters as a class. As always, research into all the racial traits of each race will make a player's decision better informed.