I use the Eclipse devlopment environment withPHPeclipse for my PHP / Drupal coding. It is not a lightweight program but it is very powerful and works fine on my computer with 1 GIG of RAM. I like that it connects to CVS and Subversion ... I have my own Subversion site to keep my code "safe" and many open source projects use CVS so right from the IDE you can get the code and create a new project.

There is quite a learning curve but its not too hard. I don't have the internal debugging working yet but ...

Sun's home page for JAVA is by definition the home page for the language... it was development and mostly still controlled by Sun.

Take a look at the beauty of CSS design at the Zen Garden where you can spend lots of time just clicking on different designs for the same basic content..

Leggo My Ego
and
Dark Rose and
Surreal Clean all have the same content and are just css style sheets on the same xhtml page..

I guess you should start at the drupal site Customization and theming -- focus on 4.7 and PHPTemplate it is the default theme engine..

Learn from ichris.ws Theme Development Checklist is a good "how-to" to go from a cool HTML / CSS page look to a drupal theme

Drupal Tutorials has a good review with some tips... I find the more different stuff I read the better I understand something - after banging my head on the desk trying it for a while..

PHP Geo Tools for Yahoo

PHP 5, JSON from pecl cvs, Map Tile API and the Yui Connection Manager. Toss them in a bag and shake and you get something like this. Enter a city name, or even a pseudo-name like Philly or SFO and hit return. Each time you enter a new name you will get a map tile for that city.

http://www.killerphp.com/

Pretty elementary but if that is what you are looking for check it out.

Zend Developer Zone PHP 101 -- for the absolute beginner. A series of 15 pretty good tutorials with working code that can help you learn what is going on ...

check out this article on zend using PHP5+

PHP SOAP EXTENSION

is this easy enough: