Web

General information sites

A List Apart

Smashing Magazine

QuirksMode

Core web tech

HTML

JavaScript

CSS

PHP

Fonts

Design

Luke Wroblewski

Yahoo design pattern library

http://www.designingsocialinterfaces.com/

http://designinginterfaces.com/

http://ui-patterns.com/

http://quince.infragistics.com/#/Main

http://box.mepholio.com/

http://www.uxmatters.com/index.php

Interface design patterns browser

Example Sites

http://www.highcharts.com/

http://www.bumblebeelabs.com/

http://actionbarsherlock.com/

http://growl.info/about

http://finegoodsmarket.com/view/

http://pupunzi.com/

Blogs

Webification (library pointers, reviews, news and interviews)

Steve Souders performance blog

Designer David Shea's blog

Tutorials and Tools

colr.og - slick site for developing color schemes

Idée labs - image search tools (by colors, tineye reverse search, more)

Wide range of subjects, including Photoshop, coding, etc

Makers of XRAY, MRI, gradient design tools and more

jsFiddle interactive js/CSS/HTML test tool

Background sprite creation

Balsamiq mockup tool

Chris Pederick, Web Developer browser extension and other useful stuff

Articles

Color theory: contrast vs. readability

Typography as a core element of design

Services

recaptcha (Google's captcha)

Marketing

http://blog.kissmetrics.com/