Gmail has the advantage of not having a "little kid" reputation and still being free. Do you ever use the webmaster/missress@neskaya.net? You probably wouldn't for something whoaprofessional, but it might be good for semi-professional. Your own domain always adds that extra something.

I registered redacted@gmail.com a couple of days ago out of fun, and I think it was probably a good idea.

You could also use your ISP e-mail if you want someone to have very little idea about who you are. (so long as the username is not hottieazn4098)