I'd be interested in using this type of service; I've tried a few but they were mostly too complicated to use, failed to work as advertised, or cost more money then hiring someone off vWorker to write a specific one-time solution.
I planned on adding more advanced features later for users to specify css selectors and stuff.
The main ability of this is a preview and adjust feature I created in there that highlights the data it "thinks" it would grab for each website.
I took a lot of notes as I was creating this.