For all of us who run in and out during winter, but don't rely on any pedometer device when running on an indoor athletic track, I just fell on some interesting and cheap usb stopwatch: junsd stopwatchhttp://www.rhardiman.plus.com/stopwatch/junsd.html
The interest lies in the fact that if you miss a lap, it will be easy to trace it through the interface on your screen looking for the unusual interval. So in the end, you just multiply the correct number of laps with the length of the lane to get your distance. You can also easily find your speed for different splits of your workout.
Here is a track lane distance calculator that can be useful for your calculations: http://www.csgnetwork.com/disttracklanecalc.html
It is far from being a gh-watch competitor, but I think might complete your gps watch for indoor training. I hope am I not offending anyone at globalsat with this thread and if I do, please just delete.
I think there one model available on ebay.