We’re getting this question a lot more lately. First, that’s awesome. Second, YOU’RE awesome for asking us first. We’ve updated our information at the bottom of the page to make things a bit more clear cut, but since we dig the way that Randall Munroe goes about it with XKCD, we’re going to follow his lead:
You are free to copy and reuse any of any of the strips in a non-commercial manner as long as you tell people where they’re from. That includes using them to make a guild banner, avatar, etc., just be sure to give us credit when you can so people can learn about the rest of our stuff. You don’t need our permission to post the strips on your personal website; just include a link back to this page. We’re also okay for the most part with the occasional posting on a professional blog, publication, or other outlet. If you’d like to do more, please contact us first. Obviously, if you know of someone not following these wishes, please let us know.