Use TextMate? Can’t stand trailing whitespace in your code?
Here is a mini-Bundle that wraps a macro around ⌘-S to strip trailing whitespace and save the doc.
“Strip Whitespace on Save”:http://underpantsgnome.com/assets/2008/10/28/Strip_Whitespace_on_Save.zip
Just unzip it and double-click it.
If you want to change the shortcut, open the Bundle Editor and change it in the settings.