Currently use auctioneer (price trends of the auction house makes for smarter purchases), ice hud (nice graphic display of your health enemy health buffs and LARGE combo points), rogue focus bars (Easy to see bar graphs detailing buffs ,debuffs , dots and the amount of time remaining on them ...very helpful), miks battle text (lets you see the damage you do in a more customizable text fashion ), im still using quest helper as i need to see if the new blizzard quest helper also displays information about mobs on mouse over, xperl (raid frames, lets you see everyone in your party whether it bg or instance, and lets u see your targets target, good for following main tank if no one is marking mobs)and titan panel (shows u your gold lets u open all bags at once).
Out of these the 2 most useful for my rogue would be rogue focus bars and xperl.