Here's something that may or may not be important when registering your own domain name:
Check on the exact contract language surrounding the ownership of 'your' domain name. Many years ago, I registered my own domain, with me as the technical and administrative contact. So I've never had problems. But some years ago, a number of people I know (and do occasional web page work for) registered names through their ISPs.
After a time, one of them (Qwest) sold their operations to MSN. The people who had domains like xyz.com were all informed (via e-mail) that their domains would no longer be valid. They would be switched over to an 'xyz.msn.com' name. Attempts to buy back the names were useless and, following the switch, the original names were sold to a domain squatting outfit.
I know that behavior is rare. More often, they (the ISP) just make it difficult to switch to a different hosting outfit. But what other horror stories do any of you have?