Let the hive mind of Engadget get that for you.
"I commonly need to boot a system from an external disc and take a snapshot of the host system. I also then need to burn a copy of the image to a DVD. While I can do it with two separate external devices, and two power supplies, and two I/O cables, it'd be nice to find a small dual-drive enclosure. It would need to have USB, eSATA, and FireWire. Either slim-line or half-height bay for the optical burner would be fine, and space for either a 2.5- or 3.5-inch hard disc. Any ideas?"
Also, MTBers will definitely pass this one up, and serious road riders, not only concerned about weight (as one other commenter said) are generally travelling in packs, going very fast and need to keep their eyes on the road. Also, serious riders with cash to burn already have computer linkable cyclocomputers that integrate with heart rate, cadence and hub-based speed sensors.