10 at the moment.
1 Warlock, 1 Mage, 1 Priest, 1 Paladin, 4 Shamans, 1 Druid, 1 Death Knight.
The first team consisting of mage, priest, warlock, paladin and shaman was the team I was playing with in BC and just starting heroics. After going through the level content of wrath I tried my luck with this setup and failed hard which was why I stopped it completely for months.
After this break I started with my paladin/4 shaman setup but I only had one shaman on 80. So I created three new shamans and leveled them with my death knight and my boomkin to 80. All my 80s got epic flying of course. I shouldnt think about it - 25k gold spent for pretty much nothing. :P