A highly cool feature found in Ogg Vorbis format (though the support in tools is not yet that visible).
Bitrate peeling means that you can take a high-bitrate stream, and reduce it to lower-bitrate stream very quickly without need to re-encode the stream.
For example, you can make a 256kbps stream for desktop usage, 128kbps stream for portable player device and 64kbps/56kbps stream for streaming on Internet radio (with dynamic bitrate adaptation!) with same effort...