Great little CSS blog with tips, tricks, examples etc.
#reference
WordPress Hooks
Database with all the plugin/API hooks available in WordPress!
Visual jQuery 1.1
Really cool manual covering jQuery 1.1.2. Click through to find out all the methods etc.
SharedBook – Developers – Documentation
SharedBook – Developers – Documentation
Reference Manual/documentation for the SharedBook API.
Writing a Plugin « WordPress Codex
Writing a Plugin « WordPress Codex
The official document on how to write a plugin for WordPress (single user).
Apache module mod_proxy
Details on the Apache module for running as a proxy/cache.
Handy one-liners for SED
Awesome list of ways to use SED to do cool stuff.
DNS Oversimplified: How to check your DNS
DNS Oversimplified: How to check your DNS
Nice simple explanations of DNS.
Practical PHP Programming Wiki
Practical PHP Programming Wiki
Interesting wiki with all sorts of guides and tips on PHP programming from really basic to quite advanced.