Out with the old. In with the new. Hope you like Springsteen.
Symbolic link idling as seen on the TF2 Facepunch Forum.
This method uses a shortcut to the LARGE steamapps folder. Goodbye 15GB copies for each Sandbox/account!

CMD COMMAND: http://dl.dropbox.com/u/7077065/steamapplink.txt
FACEPUNCH TUTORIAL: http://www.facepunch.com/showthread.php?t=1102531
Detailed instructions and files coming soon!

Launch command:
applaunch 440 -textmode -novid -nosound -noipx -nojoy -nopreload -sw -width 640 -height 480 +map itemtest