USB aquariums aren't particularly cutting-edge but we do like this recent version from Brando that lets you make stuff happen in the tank via an interactive menu on your PC.

You can turn the light on and off, feed, play and even "cure" (we assume as in heal rather than in the smoked/kipper sense) the two life-like fishy inhabitants.

$23, link below to product page that includes a video of the action.