I did Classic Raids, purely for the acheivements. (Actually finished on the weekend, did BWL and AQ40, cheated and did a pug raid on both). I did the Cen. Circle rep incase that changes with Cata... not sure I'll do the Brood Rep though. Was farming for the Polymorph Turtle scroll, but apparently that's not going away with ZG. I'll still got some of the alliance lowbie ones to do (should be fun running into Stormwind for Stockades!

Do the acheivements that will no longer be obtainable in Cata, become Feats of Strength?

Also leveling up another group for options when Cata comes out (main group is pally/3xShaman/hunter, next group is 2xDruid/DK/Priest/Warlock)

Getting trades up on a few of the toons

I might be wrong but with the new prices of heirlooms, I've gone back to the Crusader dailies, as the price hasn't changed with regards to the Champion's Seals currency.

I'm not sure about other peeps, but I still run PoS and HoR on my main team on a semi-regular basis, just to avoid getting rusty.