Bitrate Peeling is a technique used in Ogg Vorbis audio encoded streams, wherein a stream can be encoded at one bitrate but can be served at that or any lower bitrate. Bitrate Peeling is similar in overall effect to RealNetworks' technology called "SureStream", which basically creates a single media clip that contains multiple bitrates. The purpose is to provide access to the clip for people with slower Internet connections, and yet still allow people with faster connections to enjoy the higher quality content. The server automatically chooses which stream to deliver to the user, depending on the user's connection speed.
As of 2005, Ogg Vorbis bitrate peeling existed only as a concept as there was not yet an encoder capable of producing peelable datastreams.
An experimental implementation of bitrate peeling can be found here. However, re-encoding files at a lower bitrate will preserve more quality than this experimental bitrate peeler.