Im not a lawyer, but there isn't really much I found out there that can protect your IP - at least the stuff hanging out in the public domain. Sure, you can protect your IP from internal influences (venture partners, employees, etc) thru Non-Disclosures but even those aren't foolproof.
The moment your great website (and idea) goes live, someone can copy it.
Remember Goto.com who invented the Pay-Per-Click method? Fast forward today, and every major search engine now uses it.
I've had my business copied dozens of times. You can't patent ideas.
You can protect service and trademarks (Thru Trademark).
You can protect content and original works of art (Thru Copyright)
As for someone visiting your website, examining the concept, and duplicating it -- there is really nothing out there to stop it.