http://web.mit.edu/8.02t/www/802TEAL3D/visualizations/vectorfields/CrossProduct/CrossProduct.htm

for a cool applet on cross products.

other applets used for MIT multivariable calculus:

Some discovery applets on dot product, cross product

http://chortle.ccsu.edu/VectorLessons/vectorIndex.html

for an online tutorial on vectors

http://www.ies.co.jp/math/java/vector/index.html

lots of vector applets

http://www.math.umn.edu/~rogness/quadrics/

interactive gallery of quadrics