Create a form in a Google Docs spreadsheet and send it out to anyone with an email address. They won’t need to sign in, and they can respond directly from the email message or from an automatically generated web page. Creating the form is easy: start with a spreadsheet to get the form, or start by creating the form and you’ll get the spreadsheet automatically. Responses are automatically added to your spreadsheet.
I just gave it a shot, and it’s amazingly simple. I’m not sure it could be any easier than this to create surveys or signups. This sort of collaborative feature simply isn’t possible with desktop spreadsheets like Excel and Numbers. (Via Ian Betteridge.)