JQuery Mobile Framework
Codiqa's online JQuery Mobile IDE; can be used in "demo" mode for free to build elements of an app.
Intel's XDK IDE for mobile-app development
The following links provide packages that include the Apache web server, MySQL, and PHP. These simplify installation and management of this so-called LAMP (L for Linux) "stack" for building, testing, and deploying web-based applications. You might download and install on your local machine for development. From the application's standpoint PostgreSQL and MySQL will look very similar and you can easily (and should) hide the database-dependency.
WAMP stack for Windows
Complete (L)AMP stack for a variety of OSs
UNIX command-line tutorial
UNIX in 10 minutes
Another SQL Tutorial
Great PHP Site
The Webmaster's Reference Library: Web Site Design Tips and Tutorials
Bad Design Examples
RSS 2.0 Specification
Making an RSS Feed
RSS Feed Validator