06/19/08: In simple terms, DNS is like a phone book which translates human readable web addresses (say www.google.com) into numbers that your computer hardware can understand and use. ISPs (Internet service providers) have their own "copies" of this book, and some can be quite slow at looking things up for you.
OpenDNS is an alternate DNS service, that is fast, reliable and free. You can use it at home and possibly at work, and your browsing experience will likely be a little faster.
For a home network, just enter the DNS nameserver IPs into your network router, and all your home computers will be ready to go. It's easy and worth doing.
I've been using this service for about a year now, and it's been great.
