I made a flash diffuser for my external flash, mounted on a flash bracket. Hardly ever use this flash, but I saw some spectacular macro photos made with an off-camera flash, and I wanted to try it too. So, this is my set up: Pentax K-5 body, Panagor 90/2.8 macro lens with a Pentax-A 50/1.7 reversed on top, and the external flash with home made diffuser.
And here are some examples made with this combo. Just from our back garden... Quit some species to find here!