I usually dabble into building LEGO guns, such as the M1A1 Carbine, the Ray Gun from Nazi Zombies, The Ambassador from TF2, and various other things. From time to time, I'll put things other than guns like minifigures and mini-weapons for them and possibly other stuff.
LEGO MP40 with Lots of AttachmentsI am not 100% done with the pictures (my mom's camera died -_-) but I can tell you what attachments I have made for...
LEGO Ray GunI sorta stole the main build of this gun from JS9's version of this. But, as I don't have that many brown pieces, I made mine gray/black....