[16s]

I highly recommend Tuffmail. They are awesome. I am a longtime customer:

http://www.tuffmail.com/

Edit: It's not free. It costs like 2 dollars a month for the smallest account.

[poutine]

Another suggestion for tuffmail. Used them for years. Stable and does what you need.

[grosskur]

+1 for Tuffmail. Also a long time customer. My favorite feature is the admin interface that lets you manage an unlimited number of aliases and route them to specific folders, e.g., [e-mail] => INBOX/foo/, [e-mail] => INBOX/bar/. Compare this to Google Apps and Fastmail, which both seem to limit the number of aliases you can create.