Hi, I am building an app on top of Google Reader. Since users have to enter their Google Account data, I'd like to use this data to assign personal settings to each user. However, if I do so and a user would change his email adress or password(for the whole Google Account), I wouldn't be able to identify him anymore. Thus, I need to know if there's a Google Account ID or something that I can use to identify users regardless of an email adress or password. Thanks for your help!