Guitar Synth - Size: 1.5 MB - Shareware
http://www.hitsquad.com/smm/programs/GuitarSynth/

CONTROL A SYNTHESIZER IN REAL-TIME WITH YOUR GUITAR WITHOUT A MIDI PICKUP

Guitar Synth allows you to control either the synthesizer built into your soundcard or an external synthesizer, by playing your electric guitar in real-time. Unlike a hardware guitar synthesizer, Guitar Synth does not require special pickups to be attached to your guitar. You simply attach the guitar to the microphone input of your soundcard using a simple 0.25" to 5.25mm audio adapter available from electronic and audio shops.

Play the guitar and Guitar Synth will convert the audio signal from your guitar into MIDI. Hear beautiful piano chords or whatever instruments your synthesizer supports! You can even control the synthesizer using your voice, a CD or other audio input. You can also use Guitar Synth to tune your guitar.

Guitar Synth is shareware and has two separate versions. The unregistered version has no time limit on usage, but some options are restricted.

Guitar Synth - Size: 1.5 MB - Shareware
http://www.hitsquad.com/smm/programs/GuitarSynth/