Hello, PICture!
Oh believe me, i search this topic a lot, and found some projects too, but there always can be more and new ones that i don't know about
There are couple i have found and tried:
http://www.delta7.de/projekte.php#devis
http://bascom.at.ua/publ/cvetomuzyka...s_eye/1-1-0-40
http://www-user.tu-chemnitz.de/~heha..._DeluxeUSB.zip
Unfortunately, none of them do smooth light control (pwm), only on/off. Thats why i keep searching and so i found this old post, thought maybe smart people already have done such project, smooth led control on USB, music related.