racerwii
A python program using the cwiid library to time a long distance race like a 5k. racerwii displays results on a screen so could be hooked up to a projector or large LCD at the race site for timing feedback for runners.
A similar implementation in Go is at http://github.com/mzimmerman/racerwiigo which substitutes the display with a web interface and some advanced race support like assigning/editing bib #'s and importing race entries for display.