Exercise while you work -- that's whole idea behind products like treadmill workstations and the Elliptical Office Desk. And it's the same concept that brought the FitDesk to fruition.
Considering most people hate both exercising and working (no, really, you do, too), I have no idea how well these things are actually selling. On second thought, this lets you do two things you hate at the same time, so it might actually be a great solution, leaving you more time to jump on a trampoline or record your Battlefield exploits on the PS3.
Available both as a complete exercise unit or an add-on to your existing spin bike, FitDesk basically sets up a small table in place of the usual bike handles. Park your laptop there and get cracking on that spreadsheet, all while keeping up with gossip at your favorite Google+ hangout and listening to Last.fm in the background. Man, you be multi-tasking.
The actual desk attachment is made from foam core boards, with a removable cover and storage pockets on the sides. The desk is sized to accommodate both a laptop and your arms resting on it, so you can type comfortably while your legs pedal for a burning workout. As a full solution, it comes with a compact pedal desk with hand-tuned twin belts, adjustable resistance, adjustable seat height and a built-in bike computer. The included bike is foldable (for easy storage) and comes with transport wheels for pushing into a closet.
You can get the FitDesk with the bike included from Amazon, priced at $229.99. If you only want the desk, though, you can score it for $79.99.