Here is a summary of resources for getting help. Links marked with an asterisk will take you out of the wiki.
EE Coding
Getting Started with EE*, Video Tutorials*, Quick Reference Chart*, Overview, Complete Tag List, Parameters, Queries, URL Segment Variables, Troubleshooting
Official Resources
User Guide*, Knowledge Base*, Support Forums*, EE Addons*, Developer Blog*
Extending EE
Plug-ins, Modules, Extensions, Hacks
Community and Third-Party help
Downloadable Themes, Useful Sites