Low-Complexity Audio Compression? What options exist for discrete audio compression that is good quality, moderate compression (e.g. 3+:1), and low complexity (e.g. hundreds of processing cycles to encode each sample without the use of floating point), especially ones that are not patent-encumbered? The specific application is ambient sound - vocal and nonvocal audio.

I'm not very well-versed in this space of algorithms. I'm familiar with the high quality high compression algorithms, but even MP3 is too expensive for my purposes. The only low complexity moderate compression algorithm family I know is ADPCM, and I have no idea if any implementations of that could be considered good quality.

EDIT: Relevant question: what is the highest quality fixed-point ADPCM algorithm?
SBC was specifically created for this purpose. See http://en.wikipedia.org/wiki/SBC_(codec). I don't know what the current legal situation is. 

Other alternatives depend on your application: what is your target bandwidth and what type of artifacts and errors can you tolerate and which ones not.