Audio," their first album, came out, it did okay, but it continued to build over years, as more and more people became familiar with the show and wanted to own some of the group's haunting music.
If you're not familiar with the Blue Man Group, it's three men who exist without words, nearly alien curious travelers who seek to bring new sounds into the world. It's as much performance art and pantomime as it is music, but oh, what wonderful music it is.
"Audio" contains pieces of the music used in the stage show, but is not the stage show. In many ways, it was intended to be sort of a companion piece to the show, to evoke memories of things you've seen if you've seen the show, but to put them in a new light. And, it was an attempt to capture the sort of mad scientist sound that the Blue Man Group have on an audio recording.
If you've unfamiliar with the Blue Man Group, they focus on "found sound," the art of using things in the world to make music in new and unusual ways. The piece they're most known for is a sequence using PVC tubes as drum tones. (A variation of that piece is on Audio, called "PVC IV.") One of my favorite instruments is called the Piano Smasher, which is a giant gong mallet being used to strike the open strings of a piano. It's gloriously weird.
"Audio" is a good place to start with the Blue Man Group, as the second album, "The Complex," is a bit more traditional and rock oriented (although still very heavy on the BMG instrumentation despite featuring Mr. Gwen Stefani - Bush's Gavin Rossdale - on vocals for a track), and Audio still has them being excessively weird for weirdness's sake.