I use Hushmail as my "primary" email provider. I am not happy with it though. The ads, and attidue, and that mozilla won't run it, I am using netscape to run it.
I just can't seem to find an alternative that is secure, in that I can use it on any computer and nothing is stored there. Hushmail encrypts everything, so unless my passphrase is used, my email is gibberish.