Clark University
Clark University: Dave's Short Trig Course: Trigonometric Functions
The Clark University site shows and explains the graphs of the six trigonometric functions. It explains how to find an arbitrary angle measurement using trig. Also, it explains that sine and cosine functions are complementary.
Math2
Math2: Trigonometric Graphs
Sketches of the graphs of the 12 "parent," trigonometry functions are given: sine, cosine, tangent, secant, cosecant, cotangent, arcsine, arccosine, arctangent, arcsecant, arccosecant, and arccotangent.
Wolfram Research
Wolfram Math World: Secant
Graphs of the secant function, both 2-dimensional and 3-dimensional. The site from MathWorld gives the relation of secant to cosine, if you are not familiar with cosine there is a link for an understanding.
Interactive Mathematics
Interactive Mathematics: Graphs of Tan, Cot, Sec, & Csc
Several examples are presented that demonstrate how to graph the tan, cot, sec, and csc functions.