We live in the country with a well. Our water pressure is about 35 psi. We cannot run two showers at the same time, flush a toilet while someone is in the shower or run a faucet while someone is in the shower. How can we increase the water pressure to accommodate everyone? We have a holding tank that is fed by the well.

How can we increase the water pressure to accomodate everyone?

Using a gizmo like PressureBooster.com: Low Water Pressure Pump (http://www.pressurebooster.com/). Have you talked to a local plumber?

Boosting the pressure isn't going to do any good unless you have the volume to back it up.
How old is your house and what type of pipes? Copper, plasric or galvanized? What's the cut off point on the pump control box?
Was the volume and pressure always this low or did it just come on suddenly? Back to you, Tom