vector and matrix math

with all this talk of 3d coordinate transformations, i was reminded
how much i forget my basic linear algebra. i don't think i've touched
an identity matrix or dot product since 10th grade..

does anyone know of any good resources or references for learning/
relearning this stuff? actually, what i'm most interested in know is
why it works, not just how to perform certain operations. i already
have the red book, but it doesn't seem to go into much detail about
the math and the whys.

thanks!

-jonathan