Key calculator
Enter the number of sharps or flats and the name of key will appear.

Metronome - Timing relations
If you enter the original metronome marking, original timing  and desired metronome marking, you will find out how that will result in the timing.

If you enter the original metronome marking, original timing  and desired timing, you will find out how that will result in the metronome marking.

Make sure all you enter is valid.