I switched over to Ubuntu on my work laptop because I like the clean look and feel of Linux. Following are the applications I use regularly for work:
Guake - love the F12 for a heads-up display. This is my favorite command-line interface.
Chromium and Firefox browsers
Banshee - Like it better than Rhythmbox
Dropbox - super-important for sharing files with other peeps on Windows/Mac
Tomboy - like that it will back up to Ubuntu One
Polly Twitter Client - best Twitter client I could find. Supports multiple Twitter accounts.
Geany text editor with XML plugin: I don't code, so this is about all I need.
BaseX: Easily opens large XML files for querying.
Evolution Mail & Calendar with Exchange Web Services plug-in
SFLphone Voip Client - Evolution address book integration
LibreOffice Calc & Write - Word & Excel documents
Document Viewer - PDF files
