Two basic questions - post filtering - customize individual forums.

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I've forums where the post icons have been convereted into meaningful images that give a pre-description on what the following post is going to be about. You can also filter the forunms by clicking on the post icons or by sorting through a row of the icons. Icons can also be ADDED to individual forums for relevancy.

That brings me to, customizing individual forums. I've seen forums index's with normal backgrounds and then forums within these message boards have their own look and feel. how is this accomplished? I've looked all over the internet and all over this site and I can't find what im looking for, does anyone know how I can get my hands on these hacks?