Eric Persing\'s \"21st Century Grooves\",
provides 3 CDs, but I like the MM Multi mapped grooves the best for creative, interactive jamming of any groove against any other, which makes groove construction much like live improv playing. Metamorphosis provides large sets of tempo matched grooves, at every useful bpm in every 10bpm increment ranging from 50/100 to 180/360 bpm. Thus, say you are working in 140 bpm, then you can load the patch for all 70/140bpm grooves and start jamming. There are 12 gig files with Multi Mapped grooves - so having the GIG version is especially nice, as you can easily load all 12 gigs worth of say 70/140bpm\'s and go to town.