I use Nano as my text editor for Linux, I know it’s not powerful and I should really learn Vi, but I really do seem to get by with Nano just fine.
Here is a great site with a quick help sheet for the editor:
http://dwabbott.com/nano.html
Update: May31 2010
I’ve also found this site with some shortcuts:
http://linux.goeszen.com/nano-editor-keyboard-shortcuts.html