Thank you SO MUCH for this option. I discovered it today, and it was a godsend.
Click on User CP.
Click on Edit Options.
Scroll down to the Miscellaneous Options section.
It's in the last section.
Click on the forums you want to exclude.
Click Save Changes.
It filtered out a ton of stuff for me that I don't want to wade through.
<spreading virtual positive rep to anyone involved in this>