Back in the day Yahoo Pipes would have been something I'd have recommended as being a tool in this space. Here's a blog post that lists some alternatives to Yahoo Pipes and some of them look interesting for your use case, though I don't know that any of them is exactly what you're looking for.

http://www.makeuseof.com/tag/12-best-yahoo-pipes-alternative...

Also, CloudScrape:

http://cloudscrape.com/