App that shows an image with transparency so you can see through the window? Is there an Application that lets you display an image with some alpha transparency ( either in the image or in the app ) that lets you see through the image into what's beneath? (the desktop, or other windows)  

I need this for tracing over (in this case under) in a drawing application that doesn't allow importing background images.
Afloat could be a good call:
http://infinite-labs.net/afloat