Here's an archive of various Schematics and Wiring diagrams helpful to builders of homemade instruments.
This section might not be up to date, check my album Wiring Diagrams & Schematics where every diagram I've prepared is stored.
Don't see what you need? just ask and I'll be happy to create a wiring diagram for you.
A great source for easy to understand wiring diagrams is Seymour Duncan's Support Pages.
Need a diagram for wiring two Crocker pickups to independent volume controls using a 3-way switch and one tone control (to use for both pickups).