ES File explorer (wifi and stream video from your PC or NAS)
Pulse News (RSS reader with nice interface)
Songza (legit music streaming based on mood and time of day)
Do It Tomorrow (task planner, with a neat interface)
Wikipedia (Just better than going to the website)
Instagram (cool social camera)
Dood's Music Streamer (grooveshark library player, free)
Quickpic (much better than the stock image gallery browser)
Last.fm (if you're into scrobbling your tracks. If you find it bloated, get the simple last.fm scrobbler)
RealCalc Scientific Calculator (cool retro-looking calculator)
Powernote (bookmarks, note taking)
500px (beautiful interface for browsing prosumer photography)
Appbrain (easy way to discover, queue up for bulk install/deletion of apps)