For phones, I generally include my email in the greeting/home screen message.
For my iPod, I select the engraving option and use '$100 Reward. Contact: my_email'
"If this bike has not been brought into your shop by [insert your name] then it is stolen, please call me immediately on [insert your number]".
These little pieces of paper are in places like the stem, the bars, under the bar tape, in the bottom bracket, under the inner tubes, under the rim tape, in the hubs. Literally anywhere I can put them where they are likely to survive undetected by a casual user of the bike but that is likely to be discovered the first time the bike is taken into a shop for servicing. Obviously I use little bits of plastic and a permanent CD marker for the places likely to get wet (the ones under the innertubes).
I don't expect to get the bike back days after a theft, but weeks or months later I think it would work well.
More specifically, when they plug in the camera, it would likely offer to import the photos; it would do nothing with the text file.
Except that I can't read the email address.
Maybe just put a sticker on the outside of the camera?
It wont work agaisnt a hardened thief but it will on someone who just found the camera and is thinking of just keeping it.
Disclaimer- portfolio company
I'm shocked that there isn't a way to wirelessly send pictures to a tablet PC for instant studio proofing with a DSLR that saves to CompactFlash, but there doesn't seem to be.
Perhaps people could register their noise profiles with a service like Flickr and, if their camera is stolen, this noise profile could be detected in pictures found on the web.
In the days of chemical film cameras I always made sure the first shot was of a card with my name and a contact address. I recovered three films that way which had been delivered or given to the wrong people by the people developing the film. For the cost of one photo per film, it was definitely worth it.
I need to go do this again, although if I lost the camera, I doubt I'd get it back. If a reward is offered, returning someone's photos is clearly a win for the person who has them, whereas the camera might be of greater value than the (reward plus warm fuzzies minus effort).
Then again, maybe not. I'm off to take a photo ...