Is it possible to use dynamic dns resolution with a top level domain?

I'm pretty sure this is possible but I can't quite recall how to do it. Does it involved signing up with a service somewhere and running a cron job on a single system behind my home router?

Just to clarify, I want to map a domain name I own to my home IP address, which may change every few months. I am unable to get a static IP.

Any tips greatly appreciated. Thank you.