For anyone interested in web design, you gotta see this site! A resource for web developers since 1996, it has up-to-date featured articles on web issues, extensive and searchable archives on authoring, designing, interfacing, and more. For learning new skills, or brushing up on them, the "How to" library contains tutorials on a wide range of web technology topics.
Build your vocabulary one day at a time! This website is authored by a true linguaphile, who goes to untold depths to find the origin and correct usage of a word. Presented one word a day around a weekly theme (like body parts and functions, words from Greek mythology, foreign words).
A good resource for free clip art, including gif and animations, backgrounds, buttons, lines, etc.