|Permanent link to this comic: http://xkcd.com/1551/|
This work is licensed under a Creative Commons Attribution-NonCommercial 2.5 License. This means that you are free to copy and reuse any of my drawings (noncommercially) as long as you tell people where they're from. That is, you don't need my permission to post these pictures on your website (and hotlinking with is fine); just include a link back to this page.
Or you can make Livejournal icons from them, but -- if possible -- put xkcd.com in the comment field. You can use them freely (with some kind of link) in not-for-profit publications, and I'm also okay with people reprinting occasional comics (with clear attribution) in publications like books, blogs, newsletters, and presentations. If you're not sure whether your use is noncommercial, feel free to email me and ask (if you're not sure, it's probably okay).