Ubuntu - Software Checklist

Some softwares you should check out if you use Ubuntu -

• iptux - Lan messaging and file sharing app. Works with ipmessenger on windows.
• Banshee Rhythmbox - Default media player for Ubuntu (11.x 12.04 onwards). Plays music and videos only.
  
• JDownloader - Download management app. Supports free-user-downloading from most online file hosting services. Doesn't always work well with Firefox + Flashgot.
• FatRat - Another download management app. Not as great as JDownloader though IMO. But works well with Firefox + Flashgot.
• FreeMind - Mind mapping tool
• Docking Tools ** - 
• Docky
• Avant Window Navigator (AWN)
• Cairo-Dock 
• DConf Editor - For tweaking system settings. E.g. preventing/disabling automatic shutdown on critical battery level.
• XPad - Sticky notes 
• zRam - Creates a RAM based block device which acts as a swap disk, but is compressed and stored in memory. See related blog posts here.
• PlayOnLinux - A front-end for Wine to run Windows applications on Linux.
• Meld - A diff comparision tool like WinMerge.

** A good comparision and review of the docking tools - http://www.hackourlife.com/awn-vs-cairo-dock-vs-docky-mac-style-linux-docks-reviewed/