Sonic Assault has introduced MIDIMod! 1.0 – a free MIDI Data Modulator for Windows:

The idea was to create a MIDI controller/automator which produces LFO/Envelope Generator waveshapes. It can be used to control any synth/effect which doesn’t allow, or doesn’t have, it’s own internal modulator section able to be routed internally to certain controls, but does allow the controls to be automated. Alternatively, it could just be used to record contoured MIDI automation data which would normally be hard to draw manually.

Features:

• 2 LFOs with 200 real-time generated waveforms
• 2 AHDSR Envelope Generators with Selectable Contouring
• Timed / MIDI / MIDI Sync / Gate triggering
• User selectable MIDI Channel / Note / CC input triggering
• Variable Wave / Envelope output
• Linear and Waveform Displays
• Host Locked / Free Run operation
• Manual BPM override
• Data Output Reduction
• Global MIDI Reset

Requires a host program which can route MIDI data to other plug-ins in order to be used as a real time MIDI processor.

Details at the Sonic Assault site.