Nerdtool allows you to display many things directly on top of your desktop; weather reports, headline news, and system vitals are just a few uses.
Nerdtool is capable of displaying shell outputs with ANSI escaped formatting, but can also manipulate the final output's colors, size, and font. If more intricacy is desired, Nerdtool is also capable of displaying images, HTML documents, and other higher forms of media.
Features
Shell support
Image support (both local and online)
Constant file monitoring
Quartz file support
Web support
Customizeable font, color, and size
Magnetic logs and other tools for layout assistance
Accepts colored (ANSI escaped) shell output
Full import/export
Comments and Reviews
Both Geektool and Nerdtool are very nice programs, although neither have been updated for a fair while, which has led to many problems for them both. Nerdtool may have a slightly more accessible interface than geektool, however the large community around geektool is definitely a plus. The one reason I would however rate Nerdtool as the better app is it's performance, the impact on system resources is significantly lower, and as such will mean a better battery life with no loss of functionality.