Tony Amendolare at ElectroKraft has introduced Super Synth Drums - an NES cartridge that runs the machine into a drum synth.
Super Synth Drums is a genuine Nintendo NES cartridge that transforms your original NES, or clone system (Yobo, Generation Nex) into an 8 bit percussion instrument. Just plug the cartridge into your Nintendo NES system [...]

NUSofting has released Groove Analogizer, an audio controlled drum synthesizer, as freeware.
Similar to a vintage electronic drum tone generator (e.g. Simmons) the percussion sound is triggered by an audio input, not by a MIDI message.
Groove Analogizer features:

3 oscillators synth (loads as effect plug-in), triggered and shaped by the audio input in many ways.
Selection of left, [...]

Synesthesia Corporation has launched a new website for the Mandala 2.0 High-Def Drum & Synthesizer and announced that it is now taking orders for the new product.
Mandala 2.0 is the new version of Synesthesia’s high-def drum and synthesizer, co-developed with professional drummer Danny Carey of the progressive rock band Tool. The company announced the new [...]

Synesthesia’s Mandala 2.0, a high-def virtual drum and synthesizer, looks pretty awesome. It’s a USB-based drum controller & a new type of synth, too.
Here’s a video that shows off the Mandala in action:

Synesthesia has announced Mandala 2.0, a new version of the high-def virtual drum and synthesizer, co-developed with professional drummer Danny Carey of the progressive rock band Tool.
Now a computer peripheral—its USB cable plugs into PC or Mac—the Mandala 2.0 emulates an acoustic drum. According to synesthesia, it’s only drum pad that knows exactly where it’s [...]