screenshooter is great, use it.
ksnapshot is also great but it does not work in GNOME. maybe it does now actually, i am running some prehistoric versions of GNOME and KDE (still on KDE 1.1!)
Also gimp can run in either KDE and GNOME and it does instant screenshots which you can then manipulate photoshop style.
to run gimp, type:
gimp &
at a command prompt, then type
exit
to get rid of the prompt, and i think you go to "File>grab screen" or something similar from the gimp menu.