Some Sorted Links:

A really good one for all

Some References from PC Bargain Hunter

C/C++

C++ Reference
Thinking in C++ 2nd Edition by Bruce Eckel (volume1, volume2)
The cplusplus.com tutorial (local copy)
Bjarne Stroustrup's homepage (designer of c++)
C++ Tip-of-the-Day
STL (Standard Template Library Programmer's Guide) for C++
C++ Programming Language FAQ

C Programming
Programming in C: Contains a lot of useful information
Brian Kernighan's home page
Dennis Ritchie's home page
The C Programming Language
Another good reference for Programming in C
C Programming Language FAQ

Pointers to Functions Tutorial

Java:

Java API

Shell Programming:

UnixHelp
http://users.sdsc.edu/~steube/Bshell/
http://pangea.stanford.edu/computerinfo/unix/programming/shell.shtml
http://steve-parker.org/sh/sh.shtml
http://www.ooblick.com/text/sh/
http://user.it.uu.se/~matkin/documents/shell/

Perl:

Practical Perl Programming

Some Good Classes:

Formal Specification and Verification

Quick References

gdb
xemacs
vi and another one

ACM Transaction and Conference Papers for Programming Languages.

TOPLAS
SIGPLAN Notices
TACO