This is an interesting time-waster.
http://pimpmygun.doctornoob.com/help.php
So far I can't figure out how to save images beyond doing screen-grabs. But I can see using things to make up gun graphics for games. I made this one up in about 5 mins. Oh sure it probably makes no sense, but it you are doing graphics for a scifi game or some such, it could work quite well.
O0