One of the bugbears of a GPS track is the “spider trace” that you get when stationary or almost stationary. I did a search but I couldn’t find a simple application which would remove these spurious trackpoint, so I created one. “Trakclean” eliminates spurious trackpoints from a GPX track based on either a speed or distance criterion: trackpoints are eliminated either when their speed is below a threshold, or when their distance from the last good point is less than a threshold. You can select which criterion to use and can specify the threshold or just use the default of 1.0 (kmh or metres). I have made the Windows command-line version freely available at http://scunnered.pwp.blueyonder.co.uk/Trakclean.htm in case you find it useful.