One of the current trends in mathematics teaching is to introduce more technology into the classroom. Although I am far from believing that this is always a good idea, I did have very good results last year using the computer program Geometer's Sketchpad in our undergraduate geometry course (MA 460).This course is designed for students who intend to teach high school math; its purpose is to give them a firm mastery of the geometry they will teach as well as a knowledge of some more advanced topics and an understanding of the axiomatic method in mathematics generally.
Geometer's Sketchpad is a program which (among other things) can do all of the usual ruler-and-compass constructions and can measure angles, lengths, and areas. The great benefit of this is that it allows the students to do mathematical experiments and to measure the results with a high degree of accuracy.
My students demonstrated most of the main theorems experimentally before we proved them, and I would often assign homework in which they proved complicated facts that they already "knew" experimentally. This made the homework more significant for them, and it also gave them a clear understanding of what proof is good for in mathematics, since Geometer's Sketchpad, like any computer program, has round-off error. I emphasized the fact that although mathematics has (like physics) an experimental side, it also has (unlike physics) the ability to acquire knowledge with perfect accuracy by means of proof.
My students had a lot of fun with the program (one of them told me her ten-year-old son liked it, too), and many of them purchased it to use in their own teaching.