It’s called RealNames (website here), and there are problems…
(from The Economist Pocket Internet)
Additionally, I don’t know whether it requires a certain browser version of its users - no point paying millions for a “cool” keyword if only 50% of your customers are technologically equipped to use it (say hello, boo.com!).
I’m not sure how much of it is keywords, either… For any website of the form http://www.foo.com, recent versions of Netscape and probably IE will accept just the foo part. For instance, if I just enter “straightdope”, it’ll interpret it as “http://www.straightdope.com”