eFunda
E Funda: Multiple Angle
At this site from eFunda you can scroll to the middle of the page for a listing of multiple angle formulas for cos, sin, and tan.
Math Medics
S.o.s. Math: Table of Trigonometric Identities
This tutorial highlights the numerous trigonometric identites (but does not define the basic trigonometric functions).
Lawrence Hall of Science
The Math Page: Trigonometry: Trigonometric Identities
This resource clearly and thoroughly explains the many types of trigonometric identities. There are example problems solved, problems for the student to attempt, and answers to the student problems.
Wolfram Research
Wolfram Math World: Hyperbolic Functions
This site from MathWorld explains the hyperbolic function. The information is not too in-depth, but factual and quite a few links are provided for additional information on related subjects.