Lots of manufacturers make tiny video cameras. There are now plenty of ASICs that can take the output of some of these cameras, and smoosh it down into H264 or whatever, and serve it up as web data. And there are plenty of small wifi modules. I wish someone would integrate these components into something appropriate for doorbell button replacement. It could have a very small LiOn battery to keep things moving when the doorbell button gets pressed, and the remainder of the time, could be powered off of and charged by the 16VAC power that is otherwise available from the bell transformer.
Too much to ask, I guess. Would sure be nice to undo the screws and unwire my existing doorbell button, and wire up and slap something like this in its place.
–Richard