3dsMiis.com is a Nintendo 3DS fan site designed to organize 3DS QR Codes.
Nintendo 3DS offers a really neat feature called QR Codes that allow you to just take a shapshot of an image using the 3DS camera and convert it directly to a Mii. The image then provides a Mii on your Nintendo 3ds to use in 3ds games.
This site is currently in beta stage, the 3DS just came out recently so we haven't had a lot of time to really put into this site as of yet. Expect plenty of changes in the future.