This isn't just the Atari joystick equivalent of the transparent Gameboy, which had no added features except for special see-throughness. This joystick is actually hackable, and can connect up to eight other controllers through the labeled solder points.
Retro Thing's joystick lights up blue when plugged into a USB port, and is compatible with Atari, Amiga and Commodore emulators. Bundled with the joystick is a CD with over 80 suitably-retro games, and the Stella Atari 2600 emulator. It's only $29.95 too—or $44.95 with a retro t-shirt thrown in for good measure. [Reflex Audio via Retro Thing via Make]