Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
pressing command + 3/4)? Chances are you might have a ton of files left over on your desktop after a long screenshot session.

If you don't need the files piling up on your desktop and just want to paste a picture somewhere, pressing Control + Command + Shift + 3 for a full screenshot (or 4 for cross hair selection tool).

The screenshots will be copied to the clipboard where you can paste them into a document.

when done just go to edit then scroll down to show clipboard.
http://www.tuaw.com/2008/10/06/mac-101-take-screenshot-and-copy-to-clipboard/
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.