The fine folks at Common Craft specialize in creating clear and simple animated explanations of important but often confusing concepts and technologies, anything from social bookmarking and computer hardware to zombies and the electoral college. Here are their brief guides to three Web 2.0 tools that will no doubt be much discussed over the course of the day on May 1: blogs, wikis, and Twitter. Please feel free to comment if you find these useful, instructive or provocative.