Glossary of Statistical Terms
This excellent site can help you whenever you have a question about a statistical term.
http://www.stat.Berkeley.EDU/users/stark/SticiGui/Text/

Statistical Resources
The University of Michigan Documents Center has an excellent site of Statistical Resources on the web. You might wish to explore the richness of this site when you have time, or look up a particular item if you are having trouble.
http://www.lib.umich.edu/govdocs/stats.html

Statistics Everyone Should Know
This site gives a nice introduction to statistics including the mean, median, and percent.
http://robertniles.com/stats/

Median
An interesting example of the mean.
http://www.robertniles.com/stats/mean.shtml

Median
An interesting example of the median.
http://www.robertniles.com/stats/median.shtml

Mean, Median, and Mode
A comparison of the mean, median and mode is presented at these sites.
http://simon.cs.vt.edu/SoSci/Site/MMM/mmm.html
http://www.gifted.uconn.edu/siegle/research/Normal/averages.htm