Overlay... I run a photo studio in London, and I was looking for Mac software that would enable me to make a semi-transparent floating window on my computer. I wanted to be able to open any image to use as a floating positioning guide over the actual image that I'm shooting.
I use Adobe Lightroom, and I wanted to be able to float the art-director's layout over my photo in Lightroom, to check that my shot was a good fit. Sometimes I wanted to put another element of a composite over my image to check position and perspective, or I wanted to have an image visible over my Lightroom capture so I could match it.
I couldn't find any software to do this, so I wrote it myself: Overlay for Mac is the result. It works with Lightroom, Aperture, ACR or any OS X software.
Note: Now requires OS X 10.6 or later.