Moog Music is offering a free CP-251 Control Processor (normally $399) with the purchase of any Minimoog Voyager, Old School or Little Phatty synthesizer from an authorized Moog dealer through December 31, 2008, 

This is an awesome freebie – it basically turns your synth into a modular synthesizer. Based on Control Voltage technology, The CP-251 expands the sonic potential of all Moog instruments; from the Minimoog Voyager to The Moog Guitar.

Here’s a video of the CP-251 in action: