In addition to the sites below, you can find a lot of useful information -
papers, lecture notes, and surveys - on the websites of TCS researchers (easily reachable via Google).
TCS+ Seminar - TCS Community Online Seminar
Simons Institute for Computing - Simons Institute for Computing
ECCC - Electronic Colloquium on Computational Complexity
Theory of Computing Journal
Foundations and Trends in Theoretical Computer Science
Cryptology Eprint Archive
Theory Matters Wiki
Complexity Book - Website containing
draft of Computational Complexity book, written by Sanjeev Arora and Boaz Barak.
Discrete Math: Some lecture notes:
Computational Introduction to Number Theory and Algebra - by Shoup.
Expander Graphs - by Hoory, Linial, Wigderson
Coding Theory - by Madhu Sudan
Algebraic Methods in Computation - excellent lecture notes by Madhu Sudan.
Analysis of Boolean Functions - excellent book/lecture notes by Ryan O'Donnell.