Throughout my own learning of PHP, I have found the following websites to be useful. This list will be added to as I find more available resources. Naturally, I hope that PHP5 becomes a great resource as well.
List of PHP Resources:
- Tizag PHP tutorials – an oldie but goodie for some theory
- PHP Best Practices – a series of explanations – Intermediate level
- PHP Fig – The defacto standards org for writing PHP.
- PHP School – they have a command line PHP learning module, open source and free to learn from.
- PHP The Right Way – a standard & practical text covering various topics
- PHP UserGroup – a map-based user group finding app for PHP Devs
- PHP Weekly – a weekly newsletter about PHP
- A big list of PHP resources and things
- PHP.net – The manual site maintained by The PHP Group.