Thanks to Jeromy Anglim on his blog he found a great link for free e-books on mathematics from e-bookdirectory.com. There are quite a few e-books in this link which can be a great resource for rehashing and learning some new methods.
Some noted e-books in mathematics that I found to be interesting
Algorithms by Ian Craw, John Pulham
An Introduction to R by W. N. Venables, D. M. Smith
Engineering Mathematics by Ian Craw, Stuart Dagger, John Pulham
Statistics for Business and Economics by Marcelo Fernandes
Jeromy Anglim's blog is a very interesting resource for statistics, data mining, and R. Be sure to read it for its wonderful insights.