FourHead is an experimental granulator effect, despite not really being a delay or a granulator, though it lives in that realm.
It is based on an audio buffer which constantly records the input in chunks. This buffer is then read by four "play heads" which play it back as looped segments.
The length of the chunk to be played back is set independently from the length of the recorded buffer, and the pitch and start offset for each "head" can be modulated (the playback on 3 of the 4 heads can also be delayed), creating odd retriggering arpeggiations and granular-style swarms of sound.
The output can also be fed back to the record buffer for endless noisy fun.