The Repeater ($749) from Electrix is a loop-based digital "performance sampler" that can capture 16-bit, 44.1 kHz (uncompressed) loops. Internal processing is 24-bit. The number of loops you can record is limited only by the capacity of your CompactFlash card. Data is stored as WAV files and can be offloaded to a computer via a CompactFlash card reader for further editing.
Loops can be bounced and resampled. You get four tracks per loop, and tracks are stereo linkable. You can also use sound-on-sound overdubbing to create layered tracks.
Once a loop is recorded, the Loop Assist feature can use tempo-detection schemes and the sample's transients to automatically find good loop points. You can change the track's tempo, shift its pitch and its location in time, and apply stereo panning. If you want to sync loops recorded at different pitches and tempos, the Repeater allows you to do so in real time, with the twist of a knob. It can use MIDI Clock, its Advanced Tempo Detection feature, or a rotary encoder to set the bpm. Loops can be selected with MIDI Program Change messages.