Live sites stay fresh, and I don't mean blinking text and whirling icons. Links don't go bad, tired content is brought up to date, design flaws don't fester for years. Some widely linked sites fail this test. The Earth Science Site of the Week site, for example, was a great idea, but it's been dead for two years, and it hasn't had a site every week since May 1995. On the other hand, I list the Interactive Dino Skeleton , on a site that's been quiet for years, because it's absolutely unique.
Legal sites play by the rules.
They acknowledge the sources of their images and information. Instead of copying commercial articles outright, they link to them with a summary. Many sites lack one of these, and I don't list them. On the opposite side are many online college course notes , packed with good information, that are only sketchy outlines not meant for readers like you and me. Solid sites also have depth, without too many wasted pages and useless images.