Flexible Feedback Form
If you've ever had the need to do feedback forms for other things, like surveys, signup forms, contests, or anything else, this is for you.
You just make a form with any questions you want. And whatever your form asks people, their responses will be emailed to you. Neatly organized.
It's an incredibly powerful one-line function if you ever needed this kind of thing.
There's a full tutorial on it, here.