
- Basic Category Theory for Computer Scientists by Benjamin C. Pierce (from "Types and Programming Languages" fame)
- Practical Foundations of Mathematics, by Paul Taylor (has other interesting work on his homepage as well; http://www.paultaylor.eu/~pt/prafm/; somebody on HN pointed me to it, thanks!--Chapters 4,5,7)
Practical Foundations of Mathematics http://www.cs.man.ac.uk/~pt/Practical_Foundations/index.html
Linear Algebra - Gilbert Strang (Book & Videos)
Linear Algebra and Applications http://www.math.unl.edu/~tshores1/linalgtext.html
P.S. There was another Introduction to Statistics book that I am not able to find the link for.
The full text is available online, but I recommend you buy a hard copy. Oh and I can vouch that the back cover blurb is totally true.