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

Standard Deviation
A discussion of standard deviation by T. Lee Willoughby is presented here.
http://www.med.umkc.edu/tlwbiostats/variability.html
This site presents a calulator for standard deviation.
http://www.physics.csbsju.edu/stats/cstats_NROW_form.html
This site gives a nice application for standard deviation.
http://www.ricedelman.com/planning/investing/standard.asp

Measures of Dispersion
This site gives some discussion and examples of measures of dispersion.
http://hsc.uwe.ac.uk/dataanalysis/quant_mes_disp.htm