+1 for this.Grab a Garmin Forerunner. It's a normal watch style heart rate monitor but it has GPS built in so you can track your ride aswell. Logs your heart rate, elevation, speed... everything. $260. Not that much more then a Polar HRM but with a hell of alot more useful tools.
Add me for the rider 40. Got some good training features as well. Bought off ebay from chiggle cycles.I've got a Bryton Rider 40 from www.merlincycles.com and it's great. It came with a HRM and GPS and so far has been a great asset.
Hope this helps.
Cheers,
Theo