Hello LET!
Sieve, http://getsieve.com, has been under construction for past few months. In couple of months it should be ready for public usage. Currently it is in very early stage of development with minimal set of features available in a demo.
Before we go ahead with further development, I thought of getting feedback from the community. Would love to hear your thoughts. Woud you use it?
Check it out at http://getsieve.com. Do give demo a try. It showcases a "Visual Selector" tool that helps you filter a webpage to monitor for changes.
Ajit