We know what you're thinking: extreme ski biking is cool now? Or alternatively, who the hell would get on one of these? Just take our advice, next time you find yourself off-piste, keep your eyes peeled for Ktrakers -- crazy people who've bought a universal attachment that replaces the wheels of a mountain bike with a track drive and an optional front ski. Apparently the Ktrak's insane appeal comes from its ability to let cyclists ride over previously inaccessible surfaces like snow and sand, as the company's videos demonstrate. Due for a production run in early 2007 (priced at a reasonable $400 for the track and $140 for the ski), the Ktrak is apparently very easy to install and ride, and adds only 5-pounds to the average mountain bike's weight. If you can manage to convince your brain that this thing actually exists, your biggest problem is going to be getting your hands on one before everyone else: to that end, you can reserve a kit for $300, as long as you get your pre-order out before January 1.