I think I know what OP was refering to. I couldn't find any themes when I first joined either, but google searches showed threads that contained themes. The board index showed categories with multiple threads, but when clicking on a category, no threads showed up. To see threads, you have to change the option at the bottom of the page from "show threads from today" to show threads from beginning." A moderator may want to make this a sticky, or change the default settings.
Skaero: Thanks for posting those three links, I haven't seen those yet.