I spent my weekend playing, and made a sketch that counts number of shots fired (nice little 50 ms pulses), one shot with each pull of the trigger. A selector switch to choose between single shots and bursts..... and then I find this:
http://www.ibm.com/developerworks/views/opensource/libraryview.jsp?search_by=Arduino+laser
A project about building an arduino based laser tag game.
From a quick read-through, it looks pretty good, and quite a few elements from it could certainly be recycled.