The following is a complete list of available themes for the main portions (main page, archives, etc.) of my site. When you make a selection, you will be returned to this page, but in the new theme. Once you've changed themes, that theme will be in use for every page that uses it, and will stay until you change it.
Note: cookies are required for the theme change to "stick" between pages, and for it to last for the next time you're here. It will expire eventually, though (several months). If you use anything other than the default, you'll notice when that happens. If you're using Netscape 4.x, and using the read-only cookies.txt trick, then your choice will last as long as you have the browser open (even if you close that window, as long as you still have a window open). However, once you've closed all windows (browser, mail, etc.), the cookie will be gone with all the rest.
Note #2: I don't track who you are or what theme you like to have. I couldn't care less what (if anything) you use, unless you feel like dropping me a note saying what you like/don't like and why. (Constructive criticism is never a bad thing.) So I don't write down the IPs of who uses what. I just set a cookie w/ your choice. And if you feel your privacy would be invaded by that, then just leave it as default.