I purchased my own web domain - tonyohagan.co.uk - from 123-reg. The process is very easy, and having your own presence on the web is useful. For instance, when you change your Internet Service Provider, you don't have to change your email address or (if you have your own website or blog) your web address. Having bought your own domain, 123-reg will happily redirect all email or web references to wherever your email server or website actually is. For instance, mail sent to anybody@tonyohagan.co.uk just gets redirected to where my mailbox really is. Then if I change my ISP and my mailbox moves, I just change the redirection. Everyone can keep sending mail to me at tonyohagan.co.uk, and they don't need to know where it is really going to.
Here's a link to 123-reg. When you go there, you can easily check whether any domain name is free. So if you fancy being supergerbil.com* or whatdayisthis.co.uk*, check it out!
* These two domains were free on the date below, but somebody might have snapped them up by now!