The Endorphin.es Shuttle takes some of the range modules on offer from Endorphin.es and turns it into a full system.
The idea is to have a small but very flexible self contained modular system, giving you multiple different ways of using the system. on first glance you have a two voice mono synth with dual envelopes and effects and routing, however the Shuttle can be made to run in a range of different ways.
More info at Endorphin.es
Older Music Machines & the People Who Still Use Them