One thing I really like in web designs is when even the smallest elements of a site are kept in context to the subject. For instance, all of the error pages on RockBand.com have beautifully rendered rock performance themes.
A subtler example is the anti-spam challenge for comments on PacketLife.net’s pages. Most sites have a ReCAPTCHA or simple math challenge. By contrast, PacketLife offers questions that are contextual to the subject matter of the site:
(I only point this out since you’ll never see these challenges if you’re a regular PacketLife visitor and stay logged in all the time.)
P.S. And, how many bits long is an IPv6 address? That’s a number we’ll all be quoting a lot in coming months, I predict!