Depends what you want to do. Here's some that I always end up installing:
1Weather (nice looking weather app)
Amazon Appstore (a free paid app every day)
ES File Explorer (good for browsing/copying files, extracting ZIPs, etc)
imgur/photobucket/picasa/flickr (to upload your pics)
Lightbox (lets you apply filters before uploading your pics and people can comment on your pics)
PicSay Pro (like a photoshop for your phone)
PlayerPro/Winamp/etc (better music players if you want one)
QuickPic (faster gallery than stock)
Rage Faces (send jesty faces to people)
Reddit News / baconreader (reddit apps)
Tapatalk (to browse forums)
Twicca (twitter client)
Wallbase (bamf wallpaper app)
not sure what else you want, theres an app for anything.