In my mountain bike, I have around 50 PSI, and use it for jumping, freeride, light dh etc, most things really
Trials bike anything between about 15 and 30 PSI, depending on terrain/moves etc
BMX about 80 or 90
Road bikes 110
For my other bikes, and generally at work, I pump tyres up to around 40 (depending on the particular bike and pressure guidelines on the tyre sidewall)
50 PSI sounds about right to be honest, but check your tyre first.