On-line physics resources:

Quantum Information course by J. Preskill

Quantum Condensed Matter Physcis by C. Nayak
(includes Schwinger-Keldysh formalism, RG, CFT, ...)

Lecture notes on Methods of Mathematical Physics by M. Trodden

BV and BRST by Joaquim Gomis, Jordi Paris and Stuart Samuel

Books on Mathematics:

Farkas and Kra

Helgason

Hilton and Stammbach

Kirillov

Nakahara

Griffiths and Harris

On-line mathematics resources:

Math lecture notes gathered by Lemmermeyer
(including on group theory, numbers, modular forms and polyogs)

Lecture notes gathered by Flohr
(including on logarithmic CFT, group theory, BCH, affine characters, supersymmetry, etc.)

Lecture notes gathered by Levant
(on topics like Algebra, Stochastics, Geometry, Analysis, Logic, Topology, PDE, ...)

Links on algebra software (by Fuchs and Schweigert)
(note especially the on-line program LIE).

Wolfram functions site

Wolfram elementary math

Handbook of Mathematical functions by Abramowitz and Stegun