How to make possible a login with the google account?

Hi
I'd like to know how I can make log people at my site using the google mail account (gmail).
I'd like to know if there are modules and how I can make log people only with this e-mail address.
Tnx so much for the answers.

P.S.: I've downloaded a module called "glogin" but, when I go to make the login, I'm redirect at the Google page, where I must insert again the date for receive after an error message (and I don't come logged).
P.S.2: With the GMAIL Connect module, when I'm logged, appear an error message under the login form. I try to watch the mail, but I come redirect to a page of my site that hask me again the date for loggin.