Classic Arithmetics

http://www.donpotter.net/math.htm

A lot of word problems, stories of addition etc.

Base10 blocks paper printouts andother virtual manipulatives

Lessons and printouts using the base 10 manipulatives:

Base 10 Blocks printout
Base 10 Instructions
More Handmade Manipulatives Instructions
This one on using geometric shapes to learn fractions is nicely done
The Main Site