Recently I have been attempting to learn the maths required for 3D graphics, and am currently learning matrices. As a way of testing my knowledge, I wrote a quick pygame program which transforms a funky collection of lines with a matrix. It's only two-dimensional at the moment, but the same principles demonstrated here apply in 3D as well. The only difficulty is projecting 3D points onto the camera (which apparently requires a 4*4 matrix, to include translation as well). So, before my incessant ramblings completely vanquish your interest, here's a screenie of the aforementioned program:
The matrix is displayed in the bottom-right corner. Thanks go to James for coding the nifty grid-drawing section (I only had two grey axes to begin with!).