Belt Length Calculator
SDP-SI's Center Distance Calculator for determining the correct spacing between to pulleys.
Team Tentacle's Torque/Ah Calculator
This is a very helpful calculator to determine max current draw, torque, and max speed for different drive train setups.
MatWeb's Weight Caculator
For calculating the weight of a given shape when made out of common materials (aluminum, steel, polycarbonate, etc).
A downloadable free book with a lot useful information about building a fighting robot.
Designed by WAR.