Wired have a story about the as yet unusued USB port seen on the back of the Apple TV. From the article:

Apple TV is all shiny and wonderful and hard to find, but it does have a few shortcomings, such as hard drive too small to hold more than a few HD movies.

Apple bloggers and analysts suspect that may not be a problem for long, noting the as-yet unitilized USB port on the set-top box and recent talks between Apple and Miglia, which makes a variety of TV and VoIP accessories for Macs and PCs.

All the Miglia products have disappeared from the Apple Store, so it seems something could be in the works. Rumors are abound.