I bought a wireless CatEye Strada Cadence, what a waste of money. Even if it wasn't crap (it just stopped working one day - I replaced the batteries and it just shows 0 mph no matter how fast I'm going) I wouldn't have a use for it now that I've got a Garmin.

GPS bike computers can be profoundly useful and nice-to-have. If you're the type of person who might want one down the line, consider putting the money you might have spent on a wireless cyclocomputer right into a GPS.