That's if you've got ImageMagick but you should. And if you don't want to mess with the mouse, you can specify the window, such as with 'import -window root foo'. Check out the man page for the approximately 6 trillion options. Cool program (or suite of them). You can also, of course, create a script specifying the default directory to save to, a timestamped filename, any number of other options, and invoke it with a word. Then bind it to a key with your window manager. Hell of a lot more flexible and less interactive than KSnapshot.
(I'm in KDE at the moment, and missing my icewm script.)