Gwibber:
A microblog client for Facebook, Twitter,Flickr (only feeds), Google Reader, Digg and some more. Integrates into GDM nicely (haven’t tries KDE) and provides a good way to keep up to date without permanently logging into the sites. Beware: if you’re not using 9.10, go to https://launchpad.net/~gwibber-team/+archive/ppa to get the latest version and be up to date (since Facebook changed the way the friend feeds are generated/displayed, it won’t work with the basic version shipped with Ubuntu up to 9.10)

Guake:
The Guake Terminal is a handy terminal that can be displayed and hidden with a single keypress – no need to always switch back and forth and open a myriad of shells – just use Guake and its tabs.

PlayOnLinux:
POL allows for installing W32 apps in Wine more easily – it provides a lot of installation profiles for apps and games and works really nice – tried it with Safari for web debugging reasons. It also installs the windows fonts.

GNU Privacy Assistant:
Provides a means to manage your GnuPG or PGP keys and keep track of all the keys you have authorized. Very useful (you can also use the built in manager though)

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