Found an interesting post on the official WoW forums by a level 80 Feral Druid that has managed to Solo Onyxia easily, 12 minutes of work netted him 177g + T2 epics and blues.
I know how the official WoW forums likes to swallow posts so i will summarise.
He's downed the following bosses in ZG
(Been a long time since i did ZG myself, so i can't remember if all these are correct)
And he's downed Onyxia in Cat form.
For Ony he uses mangle a lot, phase 2, he goes bear and swipes, then back to cat in phase 3.
I'm looking forward to 80 myself, i also like to do