Here is a very nice list of links that I have found after many hours of searching. Hopefully this list will give you a good starting place when searching.

Apple: Cocoa
Apple: Developer Transition Resource Center (for the Intel switch)
Beginning Mac Development
Borkware
Blackhole Media: Code
BlueMac.info
Cocoa Blogs
Cocoabuilder
Cocoa Dev
Cocoa Dev Central
Cocoa Heads
CocoaDevHouse
Cocoa Examples and Source Code
Cocoa FAQ
CocoaLab
Cocoa Multithreading
Cocoa Page
CocoaRadio
Cocoa Samurai
Cocoa Text System
Cocoa Zone
Core Mac OS X and Unix Programming: Source Code
DevChannel - Getting started with Cocoa programming
Developing Free Cocoa Software
First Sips of Cocoa
Gus Mueller - Cocoa bits
Hayne of Tintagel
Introduction to Cocoa with Tutorial
jschilling.net - Software
Karelia Software's Cocoa Open Source
MacDeveCenter
Matt Gemmel: Cocoa Source Code
Mike Zornek: Cocoa Resources
Nance Software
Nathan Day's Source Code
Object Oriented User Interface Programming
OmniGroup
phildow.net
Sample Cocoa Code
Stepwise
The Cocoa Files
The Little App Factory
The Objective-C Language
Theocacao
Weekly Cocoa App Challenge
Wikibooks: Cocoa
Wikibooks: Objective-C

Helpful Frameworks/Tools/Classes

AsyncSocket - Sockets
Cocoa 3D Tutorial - OpenGL
CircularSlider - Curved slider controls
Eden Math - Open Source Calculator
F-Script - Open Source Scripting Environment
Flat Button - Dynamic Flat Button Controls
Iconara DOM framework - XML
MoKit - Various
nibTranslate - Translation
RBSplitView - Replacement for NSSplitView
Threadworker - Multithreading
Vacuous Virtuoso

Beej's Guide to C Programming
C/C++ Source Code Search Engine
C Programming
Introduction to C Programming
Programming in C
The C Library Reference Guide
The C++ Resource Network
Wikibooks: C
Wikibooks: C++

HTMLite: Perl
Perl Tutorial
Picking up Perl
Practical Perl Programming
Wikibooks: Perl

Apple: Java
Code Examples from Java Swing 2nd ed.
CodeZoo
Developing Java Application on Mac OS X with Eclipse
How to use Threads
Java 2 Standard Edition Documentation
Java Glossary
Java Programming Notes
Java Programming on the Mac
Java Tech
Java Tips
Swing Tutorial
The Java Developers Almanac 1.4
The Java Tutorial
Wikibooks: Java

Apple Developer Connection
Apple Developer Kits
Blitz
Domain of the Bored
Doxygen - Automatic code documenter
Free Programming Books
GitHub - Social coding
Google Code Search
HyperArchive
iDevApps
iDevGames
IronCoder
Mac C Carbon
MacGuides: Mac Programming
MacHack
MacMegaSite - Developer Connection
Mac OS X Guru
MacTester
MADE
Organization of Independent Software Vendors
OS X Programming Blog
OSx86 Project
Programmers' Heaven
Project Omega
SourceForge
ToxicSoftware: Blog