hello!
I was just wondering if there was any existing tool or enterprise offering the posibility to know what are the visits, referal, visits from SE to competitor's website or any domain that I dont own?

not exactly but you can try competitor analysis tools like spyfu and compete.com and there is a more expensive tool that goes as close as you can get http://www.syntryx.com

Hitwise may be good, depending on your industry. Beware that they all use a sample group - so they aren't nearly as accurate as Google Analytics/ Omniture, etc.