PiP for Mac - Always on top window preview similar to the popular windows only OnTopReplica
CThruView Transparent Image Viewer - CThruView is a free transparent image viewer that allows mouse clicks to go through the image.
PiPer - A DIY Minecraft computer to build gadgets
LayerX - An intuitive app to display transparent images on screen.
PixelPerfect - Allows developers to put a semi-transparent image overlay over the top of the developed HTML and...
Afloat - Create beautiful invoices in 3 clicks, without mistakes