[skram]

Not sure if you're looking for a hosted solution (there are less of those) or a library to build upon (google "scraper"/"crawler" and the programming language of your choice).

Either way, check out ScraperWiki: http://scraperwiki.com

Hope this helps.

[villagefool]

Interesting service, never heard of it. I am actually looking for a library/framework rather than service, I was hoping there is some "visual editor" for defining what to scrape/crawl and simplify the building process.

[skram]

Well like I said, google or even a targetted search on Github/Sourceforge will reveal a TON of libs. As for a GUI... I don't recall any free ones coming up in my search a few months back.