There are days when your DNS servers go bad and makes you wait for many a seconds before the domain-name to IP conversion takes place. Here are some alternative DNS server IP addresse, just in case your DNS servers fail and you urgently need to get some work done or your present DNS servers takes ages for the host lookup..
AT&T / Level 3 : 4.2.2.1, 4.2.2.2, 4.2.2.3, 4.2.2.4, 4.2.2.5, 4.2.2.6
OpenDNS servers : 208.67.222.222, 208.67.220.220
Definitely, OPENDNS is the way to go. Its not only fast, its secure as well. I too wrote a post on this sometime back. It can be found here
http://technofriends.wordpress.com/2007/09/15/open-dns-a-big-dns-cache/
Chow
Vaibhav