We use the Bit.ly URL shortener all the time in our emails, posts, Facebook, printed material... everywhere.
A URL shortener is service that allows you to take a really long URL that would be impossible to remember or type, and turn it into a 12 character URL that is much easier to share with others.
There are 2 important reasons to use URL shorteners:
1. For ease of distribution through emails, Facebook and especially Twitter.
2. For tracking the number of clicks on the link.
We happen to use the Bit.ly service, but there are dozens of companies providing the service now. To find the once best suited for you simply google "url shortener" for a list.
Once you have yourself set up with an account, you can start using the Bit.ly in every one of your ads, both off-line and online. Although you probably don't want to use a Bit.ly in a radio commercial; for that you should have a catchy and cool domain name that sticks in someone's head for days.
Every time someone clicks the Bit.ly link it is tracked in your Bit.ly account. You can see the tracking results in real time, unlike Google Analytics, which takes 24 hours to show results. This makes it ideal for using in emails and Facebook Updates that you send to fans. Within minutes, you will know if your message was read and if it was effective.
Taking this once step further, you may want to, and honestly you should want to, test multiple forms of your email message before sending it to your full list of subscribers. But in order to do that, you will need different Bit.ly shortened URLs.
But there's a problem inherent in the Bit.ly system. Although you are able to create multiple Bit.lys for a single URL, you will not be able to view the individual click-throughs for each version. Their tracking will only show an aggregated count of all clicks for that single original URL.
In other words, the tracking explained above for multiple email versions with multiple Bit.lys is, well, useless.
You have two options to rectify this:
1. Set up 2 different landing pages for the Bit.ly, therefore you have unique short codes.
2. Set up 2 different Bit.ly accounts and shorten the same URL in each account.
It's far easier to have a second Bit.ly account than to set up a secondary landing page. So do that.
To track you’re A/B Split tested email message, you could log into both Bit.ly accounts at the same time using two different web browsers.
And that's it; that's the Bit.ly limitation and how to get around it. Of course, you could set up another shortener account with another company other than Bit.ly, but that means you would have to learn 2 different systems, which means double the learning and management. It's not worth the effort you would put into it.