Are there any free statistical textbooks available? 
Online books include

http://davidmlane.com/hyperstat/
http://vassarstats.net/textbook/
http://www.psychstat.missouristate.edu/multibook2/mlt.htm
http://bookboon.com/uk/student/statistics
http://www.freebookcentre.net/SpecialCat/Free-Statistics-Books-Download.html

Update: I can now add my own forecasting textbook

Forecasting: principles and practice (Hyndman & Athanasopoulos, 2012)

