Bitly is one of the most used URL shortening service, that also creates QR codes for each URL you input.
TinyURL has been around nearly a decade and is often our preferred service.
Fur.ly is lets you shorten and assign multiple long URLs to one short URL. This is a great way to share a collection of links. When you open the first URL, you can move through the other ones via tiny a fur.ly toolbar at the top of the page.