Over at the thriving XDA Community Developers are busy as bees giving Samsung Galaxy S3 owners the goods!
Recognized Developer and contributor "faryaab" has put together a Android JellyBean rom for all willing .
It's called "Supernexus". Check out the thread here.
Bloatware removed , true vanilla AOSP experience promised as seen in Googles Nexus devices.
Built from source and superlight.
Head over to the thread and have a read !