A new flashy ajax-based directory manager for your site!!!

http://www.ecosmear.com/relay/

PHP Simple Authentication Using MySQL and PHP sessions

This is the easiest script I have found to use for this sort of thing. simple session-based login / register stuff for a MySQL Database and PHP sessions. it's very customisable too.. even has some info on how to adapt it to use MD5 encryption on user passwords... fun eh?

http://simpleauth.munk.me.uk/

Overlapping Images with GD

PHP ROX!!!
http://www.codewalkers.com/c/a/Miscellaneous/Overlapping-Images-with-GD/

Dynamically writing text to images with PHP + GD

http://www.gurusnetwork.com/tutorial/php_gd/

Canvas for Dynamic Graphics

http://me.eae.net/archive/2005/12/29/canvas-in-ie/
http://developer.mozilla.org/en/docs/Canvas_tutorial

using PHP to generate CSS gradients!

http://www.barelyfitz.com/projects/csscolor/

CSS Button designer - CSS BUMA

This is fun
http://css-buma.sjfrancke.nl/index.html