Are there any other places besides dreamhost that you can get domain from?

I don't see why there would be ads if you purchased something.

Anyways, yes, there are other domain registration Web sites. Most paid Web hosters do domain registration.

http://netrillium.com/register.htm
http://vizaweb.com/dnc.php
http://godaddy.com
http://smallbusiness.yahoo.com/domains