[Skywing]

I can't put my finger on it, but for some reason I just can't stop brainstorming about this concept. I think it'd need to be marketed as a lower level service than Posterous. It wouldn't create a nice web page for you, it would just store the data and let you do whatever you want with it.

I guess you're right though. If somebody was going to code something and use a database, they'd probably just go with something a little more direct.

Edit: Also, in regards to overhead of GET versus an SMTP message. I think the payload for SMTP might be about the same or maybe even less than GET in size.