First, check out the Hydraulics Engineering Design resources on Engineers Edge.
Page that I think are must see:
Standard Pipe Schedules and Sizes Chart Data
Hydraulic Actuator Cylinder Force Equation and Calculator
Velocity and Flow Capacity of Oil Schedule 40 Pipe
Velocity and Flow Capacity of Oil Schedule 80 Pipe
Velocity and Flow Capacity of Oil Schedule 160 Pipe
Also, check out ...
Fluids Flow Engineering and Design
Pipe Flow & Friction Factor Calculator
Head Pressure Loss