If you haven’t yet, don’t forget to include your vote for the new banner. Some people are ranking them, others are giving 1 or 2 favourites. Whichever design gets the most support will become the new banner for this site. FYI – to the best of my knowledge, I can’t use more than one (but if that ever changes then I will certainly do that).
Go vote!
Crommunist 
If you want to do rotating banners in the future, here is an excellent “how to” on the javascript coding behind it. http://www.tutorialcode.com/javascript/rotating-banners/
Thanks. I will suggest it to our webguru.
PZ’s Scienceblogs copy of Pharyngula loads a randomly chosen banner from a set each time the page is loaded / refreshed; I don’t know how it’s done on the SB Pharyngula, but this code does the same thing:
<SCRIPT LANGUAGE=”Javascript”>
function image() { };
image = new image();
number = 0;
image[number++] = “<img src=’banner1.jpg’ border=’0′ alt=”>”
image[number++] = “<img src=’banner2.jpg’ border=’0′ alt=”>”
image[number++] = “<img src=’banner3.jpg’ border=’0′ alt=”>”
increment = Math.floor(Math.random() * number); document.write(image[increment]);
</SCRIPT>
Sticking something like this in is dead simple if you’re just editing html manually. Messing with the blogging software might make it substantially more complex, but I wouldn’t know.
The linked article above does something different–it changes the banner at a set time interval. Which is preferable is a matter of taste, I suppose.