Someone had emailed me asking for a script that would keep the navigation "with you" as you scrolled down the page. I know I've seen these things many places (although I will add that, while somewhat convenient, I find these menus distracting from the content of the site)
I did find it, but thought it might be worthwhile to post the places I told him to search around in as well:
hotscripts.com
javascript.com
scriptsearch.com
dhtmlcentral.com
dynamicdrive.com
At the last one is where I found the script.