You probably already know how to close apps with a swipe in iOS 7 (if you don't, double tap the home button, then swipe up on the thumbnail.) But there are other cool things you can do with a simple gesture. For example, within the mail app, swiping from left to right from the very edge of your iPhone's screen can take you from a specific inbox to your list of all inboxes. The same gesture works for going back to a previous page and forward to the next page in the Safari browser, which is a great way to return to a search results page.
More: How to Use Mail in iOS 7