I love ending my emails with a witty saying or neato quote, so for the past year now, I've been composing my emails, then opening up a Terminal window and copy-pasting the output from fortune into the message before sending. There is a *much* better way of doing this, of course! Open up Script Editor and create this script (note you have to replace /path/to/fortune with the path to the fortune installation on your system):
tell application "Mail"
activate
make new outgoing message with properties ¬
{content:do shell script "/path/to/fortune", visible:true}
end tell
Save this in ~/Library/Scripts/Mail Scripts (you may have to create this folder). Open up Mail and select 'Update Scripts Menu' from the Scripts menu (the AppleScript icon between 'Window' and 'Help'). Now select the name of the script you just created and boom! Fortuned email sigs!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040503211932363