If your forum system has emoticon support built in (i.e. if it's not too much trouble) it may be a cool idea to use emotes for the icons of the different topic types. Like, that typing :env: would give you a miniature version of the Environment icon, :cha: of the Character icon, and so on. You could also consider adding separate icons for time limits and tag amounts. That way :env: :30: :3t: could give you this:

except in black, and the same height as a single line of text.

You could also have both a color and a black. :env: yielding a black icon, and :envc: yielding an icon in the same green as at topic selection when starting a session.

This suggestion is intended for the forum part of the site, but I just realized having the same emote support for comments and descriptions on the main site would be cool. :env: and such would have to be white on the main site, though.