Tremor
Tremor is a fixed-point (integerized) low-level Ogg Vorbis decoding library (BSD-liscense) designed for embedded microprocessors that can't do floating point calculations (which includes many popular Digital Audio Players lines such as the IRiver H-Series and Rio Karma). There is also talk of implementing a fixed-point encoder version of Tremor so that encoding can be done on an integerized DSP platform feasibly (see xiph.org mailing list). Tremor has helped Vorbis gain considerable hardware support amongst manufacturers in the last few years.