Forester (donationware) from Leafcutter John (leafcutterjohn.com) is nominally an audio file looper. But forget everything you know about looping — Forester BREAKs the mold. You point it to a folder containing audio files, and it selects six of them for its buffers, then extracts loops and applies various effects. Which of Forester's loops play and what effects settings are available depend on the location of a roving cursor in the forest, which is a two-dimensional array of circles. You can exert some control over the shape of the forest, and you can refill the audio buffers on the fly, but you are not in charge.
Designed in Cycling '74 Max/MSP, Forester runs as a standalone application (you don't need Max/MSP). It comes with a built-in recorder, but you can also capture the output in your DAW with an audio-routing utility such as Cycling '74 Soundflower (cycling74.com; free).
The effects include delay, pitch-shifting, reverb, and bit reduction, and you can toggle any of these off. Another toggle, called Little Loops, determines whether short loops are interwoven with the longer, more musical ones. Little Loops gives you a constant pulsating undercurrent; otherwise, you get periods of silence that are punctuated with longer audio snippets. You can constrain the area within which the cursor roams, you can turn roaming off, and you can reposition the cursor with a mouse-click. The same position produces roughly the same sound, so with a little clicking, you can ferret out a good roaming region.
As random as Forester is, it can yield musically useful results. For example, if you feed it stubs from one of your songs, turn Little Loops off, and then record the output for a while, you'll get many clips that you can work back into the song (see Web Clip 1). On the other hand, the charm of Forester is letting it roam the forest. Feed it a CD from your collection (it will read direct from your CD drive), then sit back and enjoy the ride.