is this possible?

[s0ber]

is it possible to overlay an image with another transparent so when someone drags the image to save it it saves the transparant image instead of the actual picture? this I think would stop most image theft... Along with the lil javascript thing to keep right click off...

[hyperion]

Yes, it's called watermarking.  Check the mod section.

However, the current mods do the watermark on the fly, which means a non-watermarked version is available if a user knows the URI of the photo.