Perfect post since I went through my resource bookmarks only a few days ago. I also have more brushes/textures websites listed on my online bookmark site
here :) I think I have other sites saved on my old computer so I will edit the list to include them as well!
Accessibility/Cross-browser compatibility
http://browsershots.org/ » checks one website against several browsers/systems
http://netrenderer.com/ » similar website to the one above, this one however is just for IE
Brushes
http://chokingonstatic.deviantart.com/ » different types of brushes, gallery no longer updated, though
http://redmoonstudios.com/buddha/news.html » many different brushes
http://www.brusheezy.com/ » free Photoshop brushes
CSS
http://cssprism.com/ » view and modify the colour spectrum of CSS files
http://lea.verou.me/css3patterns/ » CSS-generated patterns
http://layerstyles.org/ » creates styles for DIV layers (drop shadow, background…)
http://www.cssplay.co.uk/ » many examples for layouts and menus
http://font-combinator.com/ » preview font combinations
Font
http://www.dsg4.com/04/ » bitmap fonts (some include Japanese alphabets)
http://fontgarden.com/ » huge selection of free fonts
http://fontaddicts.livejournal.com/ » general font community, I posted here in the past when I needed help to identify certain fonts
http://www.fontspace.com/ » another website dedicated to free fonts
http://www.orange.ne.jp/~den7/ » small type foundry, some fonts are for Japanese alphabets
http://dirt2.com/ » I mainly use this website for its fonts, although it has several other graphic-related resources, including tutorials
http://www.myfonts.com/WhatTheFont/ » useful tool to identify mysterious fonts
http://www.kevinandamanda.com/fonts/ » two large collections of fonts, I think some of these aren't available on DaFont (at least they weren't when I downloaded them)
Misc/Multi-resources
http://iconverticons.com/ » free online icon convertor
http://www.bazaardesigns.com/ » various free resources (vectors, PSD, icons…)
http://freshmakers.livejournal.com/ » brushes, patterns, textures
http://graphic-affair.livejournal.com/ » brushes and textures
http://krakografik.canalblog.com/ » again brushes and textures
http://shizoo.frozen-media.de/ » brushes, textures, icons, and patterns
Patterns
http://www.stripemania.com/ » to generate striped backgrounds
http://www.theinspirationgallery.com/ » various backgrounds and borders
http://webtreats.mysitemyway.com/ » I only took patterns from this website, but it also has other Photoshop resources (brushes, PSD, custom shapes…)
Textures
http://aqueous-sun-textures.deviantart.com/ » many natural textures (wood, paper, paint…)
http://dearest.livejournal.com/ » not frequently updated, but I use these textures in almost all my layouts!
http://paleseptembre.deviantart.com/ » textures and brushes, some coloring tutorials are also available
http://www.easyelements.com/paper-textures.html » high-resolution paper textures
http://sanami276.deviantart.com/ » mostly textures (both big and icon-sized), plus a few brushes
Vectors
http://www.vecteezy.com/ » free vectors, both images and patterns