> Also, wiping your computer or using 1Password isn't going to stop you from giving your password to random web apps...
I'm not incautious with my password in the least. It's generally not hazardous to sign in with Google elsewhere, provided you trust the site. You can make an assessment of the risks and benefits of singing in through your Google account yourself on a site-by-site basis. If you have reason to believe that they've violated your trust or that a security breach has happened, you can revoke access (from that site) and change your password (or even decide to be paranoid and never login elsewhere again).