This thread is for a list of online resources that you have found valuable in helping you to write good web content. My list is below. Feel free to add your resources to this stickied thread.
Note: This thread is not for links to freelance-writer work sites. Resources only please!
Copyscape: the leading provider of services that protect your content against online plagiarism and theft.
Copyright.com: The one-stop-shop for all your text licensing needs
Good Documents.com: A web-site that discusses how to create good business documents in the linked, on-screen environment of Intranets and the Internet
Phrase Finder: Phrase Thesaurus – Ideas Generator for Writers
Poynter Online: Everything You Need to Be a Better Journalist
The Chicago Manual of Style Online
Usable Web: Guidelines for effectively writing online.
Web Style Guide