The Retro USB AVS was all over the Portland Retro Game Expo this year and looks to be one of the best ways to play your NES games on your HD TV. It sports a premium price but ships with a few cool features like built in Game Genie support, online North America Scoreboard, 4 NES gamepads and NES and famicom support.
http://www.retrousb.com/product_info.php?products_id=78
