Just a little trick for OSX users: If you need a temporary folder (for example, to place a file you need to attach to an email later), instead of filling your Desktop or any other folder, you can use the default /tmp, that gets deleted on every reboot.

To get it, simply:

• Open a Finder window
• Click Go → Go to folder… and type /private/tmp
• Once in the folder, Click File → Add to Sidebar

I find it really handy when I need to send mockups from Illustrator :-)