In this economy, free is always good. Here's a link to a free newsletter called Daily Writing Tips.
Subscribe and receive the link to download a free ebook called Basic English Grammar.
Hope Clark has three free newsletters: Funds for Writers, Funds for Writers Small Markets, and Writing Kids.
Ginny Wiehardt's Fiction Writing Blog has plenty of free information, links to markets and contests, and writing exercises.
Finally, here is a link to a free download of yWriter, a novel-writing program to keep you organized. While I don't use it exclusively, I found some good ideas here.