Resources for Web Development

Here is a shirt-ish list of sites and tools that may be of use to you if you are planning on developing a site or application for the web. Many of these have RSS feeds that I highly recommend subscribing to!

Web Sites

A site focused on news and articles about all things AJAX, as well as related topics such as Javascript, HTML, browsers, iPhones and so on.
Smashing Magazine
An online magazine will regular articles of interest to web developers. These usually entail a large number of links to other articles and pages that have been selected by the editors and readers.
Mostly articles and blogs about a wide range of things related to web development but SitePoint also has a number of books and print resources available for order.
A List Apart
If you're concerned about using web standards for your project then A List Apart is a great place to get started. There's a large number of articles relating to standards-based development (especially relating to HTML and CSS), as well as some topics relating to creating sites, such as interface design.
Yet another site with news and articles for web developers, designers, etc. Topics are those generally applicable to web development.
Yahoo! Developer Network
Broad range of articles, news, tools and links of relevance to web developers. Here you can find the Yahoo! User Interface library, full of widgety goodness, and the Design Patterns library, which is quite handy as a reference.

Development Tools

An IDE for developing web applications and the like, especially AJAX applications. Aptana is based on the Eclipse framework and runs on Java so it should be usable on most platforms. The program is in constant development and recent updates have added in support for various Javascript libraries, support for the Ruby language (the program merged with RadRails, a Ruby IDE) and even tools to assist iPhone development.
Definitely one of the the most useful tools I have come across for some time, Firebug is a Firefox extension that allows you to debug web pages "live". It lets you edit HTML, CSS, view HTTP requests and responses, use a console to log messages for your scripts, and much more. While Firebug has been integrated into Aptana, it's a good thing to have even if you're not using that IDE.
A web-testing tool that uses actual browsers to conduct tests, so you get a pretty good indication of how well your project will work once it's been deployed.
A unit testing tool for web apps that models parts of a browser.
A unit testing tool for web apps that models an HTML page.

Of course, these lists are merely the tip of the iceberg but should be good places to get started.