Has there been work after RSS to improve pub/sub protocols for websites to notify customers of changes/deltas, without the need for wholesale scraping?
I'm not aware of anything, but if someone else has some input I'd love to hear about it. FWIW, I believe Amazon does have an affiliate api that lets you search through the catalog. Same with Ebay, Alibaba, and most of the major companies. The only one I can think of that doesn't is Craigslist.
For what it's worth, I'm pretty sure that it's intentional on Craigslist's part. Due to the first come first serve nature of a lot of the free listings, it means that 'honest'/non-tool assisted users would never get a look in.
