Because of horrible, malicious virus writers who spend their days trying to figure out clever ways to take over our computers, our bank accounts and the universe, we are warned again and again to never click on anything that we don’t recognize. I used to tell students in my computer courses, “Even if your grandmother sends you a link, be suspicious. Make sure you know where you’re going before you click.”

This is great advice, or it was until a couple of years ago, when Twitter’s 140-character limits meant that we would be 11 characters over just by pasting a link such as .

With Twitter and other services, brevity was imperative. So they started creating URL shortening services that let you convert a long URL into a teeny, tiny one.

Now back to the security issue. If your grandmother sends you a long link like the one above, you’d probably trust it. But what if the link she sends is http://z.pe/56lG? You may think your grandmother has become a hacker and try to block her.

Some people have an inherent (and justified) fear of shortened URLs since you can’t see what you’re clicking on. But I have good news. A 2010 study by Zscaler Inc., a company that sells security services, looked for malicious content in 1.3 million shortened links taken from Twitter over two weeks. Just 773 of those links – 0.06 percent – were malicious. The rest were just grandmothers and regular users like you and me sharing information and resources with others.

Here are just a few URL shorteners that I use:

• A.gd (http://a.gd): Cool options like password protection, link tagging and expiration dates, plus traffic tracking.
• Bit.ly (http://bit.ly): Twitter’s built-in shortener.
• BudURL (http://budurl.com): It’s a long link, but BudURL offers all kinds of tracking information to help with your marketing.
• Is.gd (http://is.gd): I love this little guy. It has no bells or whistles, but it stands for “is good.” That makes me happy.
• Threely (http://3.ly): Lets your viewers preview the link before they click (so you can verify your grandmother is still a good person), and allows custom URLs, such as http://3.ly/Cheapskate (goes to www.cheapskatefreelancer.com, of course).
• TinyURL (http://tinyurl.com): The first service I discovered that would shrink a long link into a short one. They’re still around, but now the URL seems impossibly long.
• Unhid (www.unhid.co.cc/): This site will convert a shortened URL to its actual link so you can take a peek before clicking.

(PS — this post is a preview excerpt from the Cheapskate Freelancer book, available in October!)