Quaver is a musical calculator and look-up tool for recording engineers and composers. It can calculate the delay times and oscillator frequencies that match a given tempo to help keep things in sync. Its pitch tool can tell you the fundamental frequency of any note in the MIDI range - or perform the reverse calculation. Finally, the scale tool can tell you the notes that make up a given scale and draw the key signature.
Quaver now has a metronome in the tempo tab.