How do you configure airport extreme with dynamic dns? I have a domain via Namecheap. They support dynamic dns updates. I'd like to use my airport extreme (firmware 7.6.1) to do the DNS updates, anyone know how to accomplish this?

Here's the info about namecheap's dynamic dns.
http://www.namecheap.com/support/knowledgebase/category.aspx/11/dynamic-dns

For what it's worth, I am willing to pay the $30 a year to use DynDNS instead, if I could get instructions for setting up the Airport Extreme.
DynDNS does support Multicast DNS (mDNS), which provides the ability to do dynamic DNS and much more. They even have handy dandy instructions for setting it up with an Airport Device. It will cost you a $30/yr standard account, though.