One of the best features about the original iPods was that they continuously tracked the songs that you listened to most, letting you view this chart in a playlist. It was a bit of an eye-opener, especially for “muso” types, when what you thought would be a list dominated by Nirvana, Zeppelin and The Who ended up being won by Abba’s Dancing Queen, with the Cocktail soundtrack bringing up the rear.

It was a great leveller, and reminded us that what we think about ourselves, especially in the ways that we behave, is often very different to the reality. And the same is often true with social media. Do other people see you in the same way that you see yourself? What about Twitter? Do you really know what you tweet?

Thanks to those nice folks at the Knight Innovation Lab at Northwestern University, it’s now really easy to find out. TwXray (pronounced “Twix-Ray”) analyzes and categorizes tweets in a user’s Twitter feed to identify the topics they tweet about most, which includes everything from politics and food to energy and sports.

Just enter a username (no password required) and away you go. Here, for example, are my results.

No surprise that technology is number one. In fact, I thought that was pretty much all I wrote about. But not so. Thanks to the Olympics, some 13 percent of my tweets have recently been about sports. A further 10 percent are about education, 8 percent are about business and 4 percent are about food.

Of course, the algorithm that analyzes these tweets has to make its best guess about some of the content, and some of those guesses are going to be off. For example, I’d question my educational output if the tweet retrieved (as shown in the image) is a good example. But, overall the analysis is pretty good, and twxRay is a useful, one-page summary of a Twitter profile’s output, particularly if you’re wondering whether someone is worth following. And this could easily be developed for richer purposes, too.

“At the moment twXray provides interesting insight for individual Twitter users,” said Ryan Graff, Outreach Manager at Knight Innovation Lab. “But the base technology could be modified to provide personalized recommendations for news content or social contacts. It might also provide insight into the priorities of political candidates or an easy way to compare two entities – politicians, say, or news organizations.”

Worth a moment of your time.