At MediaStorm I take a lot of screenshots. I use the mac shortcut key command-shift-4 to capture a selection of the screen. Most of the time, I capture application settings that I send to my colleagues. The problem with command-shift-4 is that it saves the image to the desktop, an intermediary step before I attach it to an email message.
Thanks to this TUAW.com article, I discovered a solution. If you use command-shift-4 + the Control key the screenshot will be sent directly to the clipboard, making it super easy to paste in to an email while keeping your desktop clean, too.