Ask HN: Examples of beautiful code?

Do you have any examples of "beautiful" code in any language?

I don't just mean textbook code that's clean, or well-formatted, or with helpful comments, but code that is also concise and clever and solves some difficult problem elegantly. Maybe something like Duff's Device or Carmack's square root solution ... something that, when you see it, you think, "wow, that's amazing." (I'm looking for examples that might be compared to classical artwork, to make a point about programming-as-art.)

I've googled around a bit but I'm not really finding anything that stands out. jgc briefly had usethesource.com (http://web.archive.org/web/20100704053307/http://news.usethesource.com/), but unfortunately it didn't go very far.