Just thought I would drop this here:
http://www.rscustom.net/
That is for the Custom Tool Kit, which let's you create your own songs for Rocksmith.
and here:
http://forums.smithyanvil.com/index.php
Is the forum for custom songs (You must register to see the packages)
The community is reasonably active and has created around 600 new songs for your pleasure. This includes music from K-on (Fwah Fwah time), the Final Fantasy 6 theme, the Double Dragon theme, and music from Queen, Metallica, Bloodhound gang ect
Oh, and the custom songs work for Pc, Xbox 360 and PS3
Why have you not ordered the game yet?