You can sign up for an account on OpenDNS.com (it's free), or simply start using their DNS right away. Go into your Network Settings, and change your Domain Name Servers to:

208.67.220.220
208.67.222.222
If you have a small home/office network, you can do this on your hub/router/modem.
Using OpenDNS will pull up a search page if a domain doesn't exist (rather then a 404 page) but it's worth the switch for the faster and more up-to-date DNS resolution.