Useful applications in Ubuntu

• Wallpaper-tray: Automatic wallpaper changing utility
  
• Graphical Disk Map: Hard-disk space visualizer
• MusicBrainz Picard: MusicBrainz music tagger, Cross-platform
• CheckGmail: Alternative Gmail Notifier for Linux
• Dropbox: Online sync, backup and sharing utility, Cross-platform
• HandBrake: Video converter (for iPods)
• UbuntuTweak: GUI based configuration tool, for beginners
• Mendeley Desktop: Desktop and online research management tool. Integrates with CiteULike, Cross-platform 
• SMPlayer: Complete front-end for MPlayer, Cross-platform