They are quite cheap, but more importantly they have a lot of end user tools that allow you to make changes to your domain yourself for free, rather than have to get your registra to do it, which usually envolves a charge.
Try 1&1 click here Good service and support plus nice package deals. Register a domain and you get a free email facility. If you intend making a website, then you can use the 1&1 demo make up system for free,before you purchase one of the package deals.
I think the suggestions above look expensive. I use click here which costs less than £3 a year for a domain name and they throw in 50 email addresses of your choice, email forwarding to your regular email address, and also web forwarding.