There is a new project on Kickstarter that promises a low cost digital back for 35mm analog cameras:
"In the final version that will put the sale already mounted, I will use a hardware and software owned by a supplier and producer of cameras, and therefore, the quality will be higher than that presented here, because it would have a larger sensor (16mpx) and already dispose from a complete menu."
Camera details (assembled):
Some sample photos can be found in the comments section of this post.
Update - here is the new version of the camera: