Everything you "need" to know to create Web 2.0 web sites

I'm sitting here, reviewing in my head all the different pieces and parts of technology that I've used to put together my little Ajax application.

1. mySQL database (to store and manage the data)
   
2. Structured Query Language (to get info out of the database)
3. Apache (the web server program that responds to client requests for pages)
4. Mac OS X (or OS for the computer running the database, web server, etc.)
   
5. php (so the web server and database can talk to each other)
6. HTML & CSS (the skeleton of the web page that folks see in their browsers)
7. Javascript (for the dynamic interaction of AJAX)

That's a long list! Granted, I'm not saying you have to be entirely fluent with every single feature of every piece of technology on that list-- some folks would argue that by getting a proper web host that you can scratch some items, like items 1, 3 and 4, off your list entirely.
However, I believe you'll want a basic sense of familiarity so you can troubleshoot when things are not working properly or get better results when calling your web host for technical support.