I just ran across this website,
http://www.patchgeeks.com and they seem to have a wide variety of various fictional and sci-fi militaries, from Stargate to Rainbow 6.
So hope that helps you guys looking for that elusive Colonial Marines patch.
Unfortunately for me, they don't have a Killzone/Helghast patch...
still looking for a place that will do very small batches of custom patches (less than 25).