I used to have a CatEye CC-8000 "ATC" (All-Terrain Computer |8^) on my hardtail/hardnose MTB. It was a nice computer... it even had 10 memory slots. But the best part was that it was pretty well armoured and the sensor cable was really thick. It survived many crashes... one which had even sent it flying into the bushes and took me a half-hour to find it. I think the modern equivalent is the Enduro 2. Downsides to the 8000 was that it was fairly expensive ($80 at the time as I recall), didn't have cadence and only supported one bike. Currently I have a Flightdeck (3 years old) with the wired kit for my MTB and wireless on my RB. The sensor wires (on the wired bracket) and the head unit itself don't seem as rugged looking as my old 8000 but it's also come through the crashes on my MTB fine. I will have to say that for mountain biking and unless you care about the special Flightdeck features (gear indicators and whatnots), I would go with the Enduro 2. It's cheaper and provides all the other functions. For a basic computer or for RBs, I would also suggest the Velo and Mity series. A friend of mine has a Cateye OS which she found for a really good price and is pretty happy with it. Now if you're looking for all the bells and whistles, I'm certain you can spend a few hundred on ones with HRMs, PC interface kits and more gizmos you can shake a stick at. I've also seen people using their PDAs as bike computers. I think there's a few companies that sell sensor attachments for Palms. I'm not sure I'd ever go that far though.