Editor’s note: The following review is part of Macworld’s Summer of Mac Gems series. Each business day until the middle of August 2008, the Macworld staff will use the Mac Gems blog to briefly cover a favorite free or low-cost program. Visit the Mac Gems homepage for a list of past Mac Gems.

Not everybody “gets” Twitter—I understand that. It might be hard to see the appeal of a social networking service that limits its users’ messages to just 140 characters apiece. After all, what can you possibly say of value in just a couple short sentences? And how often can you keep going back to a web page and refreshing to see if your friends have seen anything interesting?

Then again, if you've been trying to use the service solely via its web interface, you’ve only been getting half the experience. In order to truly experience Twitter to the fullest, you really need to be using an external client, like the Iconfactory’s truly excellent Twitterrific 3.1.

The joys of Twitterrific are manifold. For one thing, you no longer have to go back to the website every time you want to see what your friends have been saying. Twitterrific will automatically check for messages at an interval that you decide, or let you refresh the list manually if you don't want it constantly bothering you. And Twitterrific doesn’t requiring shifting your full attention from whatever you’re doing; rather it operates as an floating application that be can be summoned or banished at will by virtue of a user-definable hot key.

The careful attention to design paid by Twitterrific’s developers means that the application be as simple or as complex as you choose. If you just want to send your updates (or “tweets”, as they’re dubbed), that’s no problem. If you want to reply to someone else’s or view their profile, that’s as easy as clicking the little arrow icon in their message. And if you want to take advantage of Twitter’s advanced features (favoriting a tweet or sending someone a direct message, for example), those functions are tucked away in a handy pop-up menu or accessible via a keyboard shorcut when Twitterrific is in the foreground.

In addition to those features, newer versions have added support for the Growl notification system, the ability to delete your own tweets directly from Twitterrific, and a secret Easter egg: the patented SonicTwoosh technology (check the Read Me for how to enable this fun little extra).

The version you download is fully functional, but unless you pay $15, Twitterrific will display an ad (tastefully integrated into your Twitter stream) once an hour. Unfortunately, about the only thing Twitterrific can’t do is solve Twitter’s persistent reliability issues.