These are a great idea for learning about design, or even for a vanity email (firstname.lastname@example.org) without the monthly fees. You do still have to purchase the domain name, but honestly the prices for .coms etc have fallen so drastically since I began, its really not a big expense. Godaddy and many others often have specials where you can get a name for around $7 a year! Many of these however will want you to register with them. Since thats their only way of making money, thats more than fair :)
DotEasy.com Free Domain HostingIncluded with domain name purchase, at the time of this review buying the domain name through them costs $25, a reasonably competitive price, especially since they offer you free hosting with that! Their free hosting package gives you 100 megs of storage, 1GB/month of data transfer, up 10 personalized email addresses (ie. email@example.com, firstname.lastname@example.org etc.), FTP access, free setup and no monthly or hidden fees.
They also offer many low priced packages if your site needs more space or bandwidth but you dont want to have to spend a lot. Again at the time of this review (their prices may have changed since) their Ultra Hosting package is only $7.95/month and includes 1000 MB storage, 20 GB monthly traffic, 100 email accounts, PHP / MySQL / CGI /SSL / Frontpage etc.