Bitly is a awesome, free tool! You simply copy and paste a link you want to share into their toolbar, and you are given a MUCH shorter version of the link.
It's great for sites like Twitter where you want to post a link, but the 140 Twitter character limit makes it important to get a shorter link.
Bitly also allows users to generate QR codes!
Another great option is from Google! Check out their URL Shortener!