Added ~/.closure-emacs-projects file.
You can put newline separated paths that point to your differnt closure projects as well as the google closure api.

Added closure-add-require-line and closure-super-jump

add require line will try adding the line under your current cursor to the require lines at the top of the file.

closure-super-jump will try to go to the file that matches your super class.

Both command require you to setup the project file to locate your files.

Both use grep and awk.  Hope you have that on your system... :-)