If I had the talent, I would volunteer to do it, but maybe someone would be willing to create a youtube slideshow or something that shows screen caps and/or pictures from the site (and ENnies) through the years would be cool - along with some memorable posts from the archives (such as Gygax posts or maybe even some of the first posts from memorable threads like shilsen's paladin thread or some of the more popular story hours). It could also feature some shots from the archived pages Eric links to above.
Edit - and if we want to get sentimental, maybe a part of it could honor those who have passed, such as angelsboi.