A few links...

All sorts: http://www.tc.cornell.edu/CTC-Main/Services/Education

Plotting: http://www.autograph-maths.com/ - Sec. & College

Geometry, trig, calculus: http://www.ies.co.jp/math/java/ - Sec. & College

Knots: http://www.math.ru.nl/knopen/art_gallery.html - jpg's

Math's links: http://dir.yahoo.com/Science/Mathematics/ - the works!

Various resources: http://archives.math.utk.edu/ - Sec. & College

Edit mathematical surfaces: http://www.dpgraph.com for Sec & College

Manipulatives: http://matti.usu.edu/nlvm/nav/category_g_2_t_1.html for Sec & College

Research on fractions: http://education.umn.edu/rationalnumberproject/92_2.html

Ambleside School: http://www.amblesideprimary.com/ambleweb/numeracy.htm

Surfaces: http://www.eg-models.de/ Choose Models. Applet not Image. Choose item. Drag model.