Google Spreadsheets has a new feature that lets you create a form to accept data. When you go to the Share tab, there's a new option to "invite people to fill out a form". The form is very simple and can be customized by changing the order of entries, their labels and the type of answers. It's also a nice way to get feedback people who wouldn't normally collaborate on a spreadsheet.
You can create forms from spreadsheets or using this URL. To keep track of your forms, add this gadget to iGoogle.
I created a form that lets you add your favorite Google service (the form has a public page that I embedded below) and here's the entire spreadsheet with all the answers.
Update. Here are the results of your votes: