Google, a company with 20,000 employees and $24 billion in revenue in 2009, is being challenged–by a guy in Philadelphia.

Gabriel Weinberg is the coder behind Duck Duck Go. It’s a search engine that is profoundly–some might say radically–private. Unlike Google, it doesn’t build a user profile for you, store your IP address, or collect any other information that could ever tie a particular search to you.

That makes it impossible, for example, for a future more-evil version of Weinberg (or his company, were someone to buy it) to exploit that data by selling it to advertisers without your permission (as Digg, MySpace, Facebook, and others have done). Or for the company to accidentally make search data public so that someone can connect whole strings of searches to the individuals who conducted them (as was done with AOL data in 2006). Or for a more intrusive U.S. or foreign government to successfully subpoena your search history.

Better yet, as of a few days ago, Duck Duck Go searches plug a gaping security hole few users have ever thought of–the fact that every time you conduct a search on Google, your search terms are passed to the site(s) you click on after conducting that search.

To understand why that’s important, Google something you’d rather was kept private, and click on the top search result. Now the webmaster of that site has both the terms you used to find that site and your IP address. As the RIAA has illustrated, this is another way to identify you directly.

Of course, what’s a search engine worth if it doesn’t give useful results? Surprisingly, considering its (so far) modest scope, this is an area where Duck Duck Go also shines. Apparently, one of the forces that motivated Weinberg to build it was the creeping ascendancy of spammy pseudo-content on Google. Duck Duck Go feels like a more-cultivated version of the web–fast, informative results without all the dross.

While it has its own web crawler and web index, Duck Duck Go also pulls results from Microsoft’s Bing and Yahoo’s BOSS search APIs, so a lot of what you’re getting are results you could find on those search engines, anyway. What sets DDG apart, however, is the way those results are parsed, re-ordered, and displayed on a page that feels like it was built by a designer instead of an ubernerd. In other words, in some ways it’s a better user experience, and with an array of customizations sure to please the internet-savvy designer / hacker / open source geek that are sure to be its early adopters.

Its search rendered friendly and usable again–and most importantly, totally private. After all, your web browser has an anonymous / incognito mode–shouldn’t your search engine have one too?