Linux Desktop March 2011

Synapse - A fast, lightweight, and sexy semantic launcher. Available in Ubuntu through PPA ppa:synapse-core/ppa.
Docky - An attractive and functional program launcher and window manager that resembles the OSX dock and the Windows 7 taskbar. Available in default Ubuntu repositories.
Gloobus - An indispensible GNOME program that provides the ability to quickly preview most file types in a sleek format and a coverflow view for folders. Available in Ubuntu through PPA ppa:gloobus-dev/gloobus-preview.
Banshee - In my opinion the best Linux music player. Docky plugin provides outstanding integration. Available in the default Ubuntu repositories, but additional updates in PPA ppa:banshee-team/ppa.
Tracker Search Tool - Desktop indexing and search tool for GNOME that provides easy access to your hard-to-find files