Here's some of my favourite/interesting links from the www that help me with web development!
Author: Easy Mod ReWrite
Without having to manually create each subdomain you can setup some rewrite rules which dynamically point to the path of your choice.
Author: David Knell
Lets you produce complex crontab timing schedules through a friendly GUI.
Gives you the percentage of users that are currently using IE6. Also has archived statistical data.
Author: Mat Marquis, Aaaron Forsander, Connor Montgomery, Paul Irish, Divya Manian, Nicolas Gallagher, Addy Osmani
A great area to learn something new, contribute to the web community and much more.
Author: Yahoo Developer Network
Easily compress multiple images and retain the same file structure as orginally uploaded. Excellent resource for every web designer
Tilt is a Firefox extension that lets you visualize any web page DOM tree in 3D. It is being developed by Victor Porof (3D developer responsible with the Firefox extension itself), along with Cedric Vivier (creating a WebGL optimized equivalent to the privileged canvas.drawWindow
Author: Paul Irish
HTML5 Boilerplate is the professional badass's base HTML/CSS/JS template for a fast, robust and future-proof site.
Author: Mike Plate
Excellent way to see the capabilities of CSS3 with an easy and intuative GUI.
Author: Chris Shiftlett & Sean Coates
Each day in December developer tips are posted (started 2007)