DGT (Digital Guitar Tuner) is a Windows95, Windows NT software, which let's you accurately tune your guitar using direct input or microphone.
Features:

• High accuracy (uses 16 bit / 44100 Hz input!)
• You can tune guitars with no signal output (through microphone)
• 27 different tuning types (standard, lowered, dropped, open tunings,
• Hawaiian etc.)
• Modulation of root frequency
• Tuning with midi tones
• Nice and simple environment

See more about Digital Guitar Tuner at it homepage...