Here's some of my favourite/interesting links from the www that help me with web development!
Author: Nettuts (Burak Guzel)
Talks about 9 inbuilt PHP functions you may not know about and how you can use them.
Great how to guide for getting tweets setup with your PHP scripts!
Author: Net Tuts
Great mini-series about how to develop in PHP framework CodeIgniter
Author: Chris Shiftlett & Sean Coates
Each day in December developer tips are posted (started 2007)
Author: G Skinner
Excellent Regular Expression Playground
designed & developed by Alex Pashley.