These are a few buttons I've found around the place.

First the standard sized buttons

NeoPets This is a rather addictive site where the idea is to look after a pet. At least that was the idea at first, now it's a site with lots of games, an entier economy and other cool stuff.

Secretly_Irving

L-Space This is a link to the main Terry Pratchett web site, named for the theory of L-Space mentioned in several of his books

Mersenne Prime search This site is about the distributed 500+ GFLOP/s supercomputer being used in the search for mersenne primes, and how you can stop wasting CPU cycles and be a part of something bigger.

Big Brother is a network and systems monitor that has the advantage of being small, easily extensible, and good looking.   Oh, and I'm co-developer.

Linux Now! Lots of links to Linux resources.

The Zero Official pages of Andrew Vachss.

Then those of almost the right size

I'm RSAC-rated, not X-rated. This is a rating system where you can say what type of content your site has, making it possible to pre-screen it. It's very easy to get any rating you want here, but since I don't actually see any reason for advertising anything I don't have, I've ended up with a rating saying essentially that there's nothing of interest to kids on my pages, so it's safe for them to see them. :)

Since the rating system is american, there is no way to indicate that my pages are violence free, just that any violence in them are sports related, so they should really be rated -1 on that scale.

Open Content is an interesting concept with obvious roots in the Open Source movement but with several interesting twists, such as mandatory change tracking and crediting.

Absurd Notions

Then those of just about the right shape

Bob The Angry Flower is a surreal and strange but (to the everlasting regret of its author) not offensive cartoon. Archive accessible online.

Mail me if you have an interesting button I should have a look at.
Note that I'm only interested in 'standard' ~88x~31 pixel buttons, and I deside if I'll put it here on whether I find the link interesting or not.