From the "completely out of left field department":

Now available in stores is the DreamStation, a cool little Playstation -> Dreamcast joystick adaptor which enables you to use your Playstation Dual Shock controllers on the Dreamcast, all the Dreamcast force feedback vibration functions are supported. Almost too cool considering that from what I've heard - theres a lot of supposed force feedback on Sonic Adventure. ^_^

Source: Sega X