Google has just launched a public DNS similar to OpenDNS as alternative to the ISP DNS.
Google DNS: 8.8.8.8 and 8.8.4.4
Why does DNS matter?
The DNS protocol is an important part of the web’s infrastructure, serving as the Internet’s phone book: every time you visit a website, your computer performs a DNS lookup. Complex pages often require multiple DNS lookups before they start loading, so your computer may be performing hundreds of lookups a day.
http://code.google.com/speed/public-dns/
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OpenDNS: 208.67.222.222 and 208.67.220.220