Online statistical calculators: Graphpad
www.graphpad.com/quickcalcs/index.cfm

Online statistical calculators: Vassar
http://faculty.vassar.edu/lowry/VassarStats.html

Free Statistics
www.freestatistics.info

SPSS Tutorial
http://it.chass.ncsu.edu/training/SPSS/

HyperStat Online Statistics Textbook
http://davidmlane.com/hyperstat/index.html

Selecting statistical tests: a decision aid tool
http://www.socialresearchmethods.net/selstat/ssstart.htm