If you hit Alt+Print (I think it was Alt, perhaps it could also be Shift or Ctrl) will make a screenshot of the selected window in the foreground under Gnome. This is this very usefull and make a screenshot of a special region redundantly for me....
Sorry, I haven't read carefully
.If you use Compiz, you can press the 'Super'-key (it is the Windows-key on most x86 PCs) and then select a region. This will produce a screenshot of this region.
