I have my domain with
http://www.lcn.biz/ which offer a free fowarding service, so you can recieve any mail from joe @ bloggs.com to any e-mail you like.
Problem is, without hosting, any mail sent back out would arrive as from joebloggs @ mailprovider.com
I agree with what Rob says, if you end up paying for a domain, you might as well spend a little bit extra a month and get hosted e-mail. Much more flexible
http://www.1and1.co.uk are very cheap for that. Apparently its usually 69p per month which is £9 per year (and from £2.99 for the domain)