Apple accessory maker Sonnet Technologies offers the MacCuff mini.

The MacCuff mini is a bracket to attach the Apple Mac mini at the back of a LCD monitor.

You can also use the MacCuff to mount the compact Mac mini under a desk or table, while retaining full access to all of its ports and the disc slot.
Most LCD monitors have open VESA mounting holes on the back that provide an ideal spot to attach a MacCuff mini. The Sonnet MacCuff back-of-monitor mounting system includes a 0.3m (12-inch) DVI-to-VGA cable.
Sonnet Technologies sells the MacCuff for $49.95. Via the Sonnet site. This is a neat product, now let's hope the recent rumor that Apple is stopping the Mac mini are not true.