http://www.southparkstudios.com/ (Thanks GTPJOE90) or http://allsp.com/
All the episodes for free!
Does anyone know of any other shows that have sites like this?
http://www.hulu.com/ <~~~Fantastic! (Thanks Chleby)
http://watch.thecomedynetwork.ca/#clip107166 (Thanks Meemperor)