On a more hi tech note, check out:
http://www.cerevellum.com/
The Cerevellum's main unit mounts front and center on your handlebars, and then you plug in USB modules that give you GPS capability, heart rate readings, and power output is even possible. It even gives you eyes in the back of your head.
Its digital rearview mirror feeds video onto its screen from a tiny camera mounted on the bike's handlebar plug or on the seat post. This thing is just in the prototype stage thus far.
The pricing ain't cheap. A fully tricked out system will cost you as much as a laptop, with the main unit costing a hefty $300, a speedometer/odometer (cyclometer) module is $60, $200 for GPS and then it's $800 for that power meter. OuchHope fully for all you guys, this sunday will be acceptable weatherwise.... 60's, sunny, dry.