Due to my current status as email junkie, I give the best buttons award to Peachpit Press for their set of three yellow smiley buttons, a normal smiley, a wink, and a kiss. I picked up the buttons and stared at them for a few seconds the right way up, not getting it until I turned them on their sides the way smileys were meant to be. Runner-up goes to Wired magazine (supposedly the Rolling Stone of the computer world) for their "Get Wired" buttons. I haven't read much in the premiere issue of Wired yet, but it looks interesting and might be worth checking out at $20 per year.
Wired -- 800/769-4733