That’s what Dapper allows you to do. It allows you to build web applications and mashups using data from any website on the Internet.
For example, AskTom has three RSS feeds available: just updated, hot articles and most popular. The just updated feed includes updates to new and old questions. It would have been nice if there was a feed for new questions only, in other words, a feed that gets updated only when a new question (and Tom’s answer) is posted on the website.
I had fun playing with Dapper. Although there are other services, like Feed43 and Ponyfish, that allow you to create your own RSS feeds from almost any web page, unlike others, in addition to RSS, Dapper can also output XML, HTML, CSV, JSON, Google gadgets, Netvibes modules and more.