We've been thinking about this idea for a long time. For example, I'm in the market for a platform bed (because right now my mattress is on the floor), but I'm not going to check every day. This application would probably be similar to EBay's "Want It Now" application, but would be more geographically based. It's a great idea, and I think we put it on our YC application (as one of the ideas we thought about).

Ya... exactly what I was thinking... for what I need right now, I wouldn't travel to Austin or Houston (I'm in the Dallas area), but for other things (cars), I would want to know when a 68 corvette comes into Austin, Houston or Dallas.

This is a pretty good implementation of your idea. http://www.craig2mail.com/ I've used it to find items that are rarely posted.

Edit: my bad, they got shut down by Craigslist http://www.craig2mail.com/craigs.html

Aside: What is up with CL? Their policies seem very short sighted.

Maybe a person could suggest they keep there system "pure" the way they want it and let you setup some "enhancements" that people would pay for or would be ad supported (by google adwords (ads on the ads, I know that sounds kind of strange)) then share the revenue.

I believe they just don't want to lose control but at the same time they want to keep there system "pure".

The problem with that kind of thing is polling the servers of Craigslist, I suppose. Would Craigslist allow it? Suppose you have thousands of items to poll for every day.

Ya... I think they busted that one guy that was doing the CL pictures... Maybe you could use the google cache of CL? Seems the site is indexed quite quickly...

Not sure how to monetize it either...