TempoPerfect Metronome - TempoPerfect is a free software metronome.
Metronomus - Powerful and beautiful online metronome
afractal Metronome - Highly perfomant, easy to use, minimalistic digital metronome desktop app.
AudioKit Hey Metronome - Visit the post for more.
Open Metronome - Open Metronome, a Free Open Source Metronome for Windows Mobile and Pocket PC.
MyGuitarTuner.com - Online microphone tuner for guitar, ukulele, violin and other instruments. Tune by ear or using the microphone of your device. It's fast and accurate algorithm makes it one of the best online microphone tuners available.