Is there a simple way to make a block, such as the themes selection block, visible only in the View Account page? I want the user to be able to select the theme they use, but I want to keep away clutter on other pages so it seems the best place for the block would be on the user's own account page. I don't see it in the list of pages for it to appear visible on, is there a way to make it appear only there?

Not until XOOPS 2.2, I'm afraid.

Also, in XOOPS 2.2, you will be able to put a theme select in the user's profile which will remember the theme, the next time the user logs in.