What does HackerNews think of chicago-ug-math-bib?
Chicago undergraduate mathematics bibliography
Here's a good list of books: https://github.com/ystael/chicago-ug-math-bib
https://github.com/ystael/chicago-ug-math-bib (updated Univ of Chicago bibliography
http://math.ucr.edu/home/baez/books.html
http://www.maths.cam.ac.uk/undergrad/course/schedules.pdf
______________________
and 2 i got from HN and /r/machineLearning
http://www.reddit.com/r/MachineLearning/comments/1jeawf/mach...
https://github.com/vhf/free-programming-books/blob/master/fr...
________________________
finally, the "Maths for PHysics" texts
http://www.scribd.com/doc/156523189/Boas-mathematical-Method...
http://www.goldbart.gatech.edu/PG_MS_MfP.htm
http://www.scribd.com/doc/91670553/Arfken-Math-Physics
___________________
(if i had to recommend only one book, it would be the Boas, or maybe Princeton Companion: http://press.princeton.edu/titles/8350.html