Bleow is an amazing site with free video lessons on almost every topic in math or science!
http://www.khanacademy.org/
Below are some sites that talk about multiplication and division with positive and negative numbers.
http://www.mathsisfun.com/multiplying-negatives.html
http://mathforum.org/dr.math/faq/faq.negxneg.html
http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/negative.html
More fun math game sites:
http://www.funbrain.com/math/index.html
http://www.funbrain.com/sudoku/Sudoku.html
Webquest Sites:
http://www.mathgoodies.com/webquests/integers_and_science/
http://www.mathgoodies.com/webquests/scientific_notation/
http://www.mathgoodies.com/webquests/climate/
http://www.mathgoodies.com/webquests/sports/
http://www.mathgoodies.com/webquests/number_theory/
http://www.mathgoodies.com/webquests/Percent_Daily_Life/