Wil Wheaton writes about writing. He links to a couple of articles on Mental Floss: 4 Must-Read Books For Aspiring Writers (Telling Lies For Fun And Profit sounds interesting) and Five Lessons In Grammar. Also, I came across this article on the site about punctuation. Again, if you aren't reading Mental Floss the magazine, try out Mental Floss the blog. It's more various than just writing tips, there's something for everyone.