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.

iTunes lets you rip multiple tracks from an audio CD as a single track. But what do you use if you want to combine tracks that have already been ripped? Why, Join Together 5.2.1, of course.

This AppleScript Studio application can take tracks you’ve imported from a playlist in your iTunes library and, as the name suggests, join them into a single AAC-encoded file.

Join Together is particularly useful for audiobooks made up of many small files. It can not only join these tracks but also save them in iTunes' .m4b audiobook file format. If you've installed Apple Chapter Tool, Join Together can create chapter marks within such files.