Originally Posted by WetWired

It really is simple. No php involved.
In your admin CP, goto vBulletin Options.
Click Forums Home Page Options.
For "Depth of Forums" set 3.
Go to the botton and hit update settings.

Okay, so now vB will attempt to display 3 levels of forums on forum home (Catagory, forum, and subforum). Only thing is that it doesn't know what to display for the 3rd level, so it displays nothing. You need to add the templates forumhome_forumbit_level3_post and forumhome_forumbit_level3_nopost to each of the template sets that you want the sub forums displayed on. My personal recomendation is to copy forumdisplay_forumbit_level1_nopost to forumhome_forumbit_level2_nopost, forumdisplay_forumbit_level1_post to forumhome_forumbit_level2_post, forumdisplay_forumbit_level2_nopost to forumhome_forumbit_level3_nopost, and forumdisplay_forumbit_level2_post to forumhome_forumbit_level3_post for a good start.