Slar is good stuff. Silverlight Augmented Reality Toolkit. Easy to use as well.
Very easy to use, used my own custom .pat file.
I ran into a couple of errors, 1. Don’t host inside of a web app. 2. Copy the DLL’s to a FAT32 drive then back and re-reference. It’s like the power point and word unblock, but for DLL’s and for some reason there isn’t a way to do this. If you don’t have access to a FAT 32 drive you can just use sysinternals stream. Just Bing that.