I've just noticed - I seem to choose a different pre-expansion "hobby" each time.
- In vanilla WoW it was the old PvP ladder (Knight-Captain Leafshine at your service)
- In Burning Crusade it was playing the shard market on the Auction House with Boltcracker
- In Wrath of the Lich King it seems to be Achievement hunting (working on Loremaster right now)
I wonder what it will be between Cataclysm and expansion 4?