@thompsone, thank you for your hard work on this! Could I trouble you for a bit more information as to how to implement it? Which files do I edit to remove ads on just one of my forums?

Never mind, I got it working! If youre a total newb like me, here's step by step instructions:

1. Customization > Themes > Find your chosen theme and click 'Edit HTML and CSS'
2. Using the search bar, search your templates for "advertisement=". You will find a line such as "{advertisement="ad_global_header"}". Copy and paste the code to replace that line, making sure that you change "{advertisement="ad_tag_here"}" to the original line's contents - in this case "ad_global_header".
3. Change the section in the code saying "forum_id_1, forum_id_2, forum_id_3, forum_id_4, and_so_on" to the forum IDs that you don't want your ads to show on. You can find these IDs by hovering over your forum link and seeing the number in the URL.