Can anyone recommend a simple, inexpensive, odometer/speedometer cycling computer? I don't need calorie counting/wattage etc. frills, just something aesthetically pleasing and weatherproof. Ideally it would be easy to switch between two bikes.

Thanks.

I've got the Cateye Velo 8 ($30). It counts calories but I had to have that feature to get the avg MPH feature, which I wanted. You can get the Velo 5 for about $5 less sans calorie counter or avg spd.

I don't know about the aesthetics of them...they're not very noticeable. I don't know of any computer that can easily be switched between bikes, however, there is probably one out there.

Cytek VDO15+. (Wireless.)

I've got one of the Knog N.E.R.D 9-function computers, I think it was about $50. Memory for two bikes, simplest mounting system ever, and wireless.

The magnet/sensor can be a little finicky when just starting out, but I've never had it mess up once I'm situated and riding.

Heartily recommend Planet Bike Protege 9.0. Can switch between 2 bikes - you have to buy the cable+mount for the second bike though. Manufacturer warranties it to be weatherproof for life! Elegant design - no buttons to fiddle with - just push the whole unit. Comes in both the wired and wireless versions.

I use one of these.
It comes in a wireless version too if that's your steez, but the actual "computer part" can still be easily detached.
It comes with a Cadence gizmo too, and can also be set up for two bikes if you buy the extra cable/mounts.
Haven't tested the waterproofness yet.

Cat Eye wireless.

+1. best computer i've ever used/seen