I will recommend books that I have and books that I heard of:
Books that sparked my interest in all of Mathematics (BTW, I'll be glad if you recommend any Abstract Algebra books):
- Calculus, Howard Anton.
- Calculus, Spivak
- Advanced Engineering Mathematics, Erwin Kreyszig
- Elementary Number Theory, David Burton.
Computer Science/Engineering:
- Data Structures and Algorithms, Adam Drozdek
- Digital Design, Morris Mano
- David Patterson and John Hennesey's books
- Mastering Embedded Linux Programming, Chris Simmonds.