Additional forms options for Google Apps users
Collecting respondents' email addresses
If you use Google Apps, you can record the email addresses of the people who fill out your form. To do this, select the checkbox next to 'Automatically collect respondent's yourdomain.com username' when you create the form. Recipients of your survey will see a message at the top of the form explaining that their username will be collected automatically.
You can also require your respondents to sign in to view and fill out a form. This provides an additional layer of security for sensitive forms.
Sharing the form outside of your domain
If you'd like to collect responses from users that are not within your domain, make sure you've unchecked the box next to "Require [domain] login to view this form".