Basic Statistics
mode, mean, median, range
http://www.slidermath.com/probs/Range.shtml
http://www.bbc.co.uk/schools/ks2bitesize/maths/data/mode_median_mean_range/play.shtml
(take a couple of mins to load)
http://jmathpage.com/middleschoolmath/jmsmstatistics.html
http://www.cimt.plymouth.ac.uk/projects/mepres/book8/bk8i5/bk8_5i2.htm
Scatter plot
http://regentsprep.org/REgents/math/ALGEBRA/AD4/indexAD4.htm
box and whisker