Macromedia Flash is a powerful and robust development tool. Because of its graphical, sound, and animation capabilities (and ubiquitous browser plug-in), major companies employ it in their website development (see www.nike.com or www.espn.com). These same features also make Flash a valuable environment for building multi-representational "movies" (a Flash term analogous to "applet" in Java) to illustrate mathematical ideas or simulate mathematical situations. The National Council of Teachers of Mathematics' (NCTM, 2000) Principles and Standards for School Mathematics includes the Technology Principle as one of the six principles characterizing high-quality mathematics education. The Technology Principle states, "Technology is essential in teaching and learning mathematics; it influences the mathematics that is taught and enhances students' learning. This article contains brief descriptions of Flash movies that have been created to support mathematics learning and investigations through visualization, as envisioned in the Principles and Standards.