Here are some ideas for rather simple X programs that might make mouse cursors easier to track.
A more demanding project would be mouse trails à la windoze, i. e. when the mouse is moved and the mouse cursor needs to be drawn in a different position, then the old mouse cursor does not disappear at once, but after a short delay. Mouse trails would be probably best implemented in a X server, but it might be feasible to do it as a X client, or better as a proxy server (see section Technical discussion for details).