Reply To: One forum to rule them all
I know it is not the proposed solution by @Chicazul, but in the mean time I threw together a UserScript you can install that will let you hide and show forums (and all threads from those forums).
If you are using Firefox, you need the Greasemonkey extension: https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/
Once installed, go to this url and you should get a prompt to install: http://loverevolution21.com/ThreadBlock.user.js
For Chrome, the process is even more convoluted due to their dumb new policy.
2. It should trigger a download of the script (you can ignore the warning)
3. Open chrome://chrome/extensions/ in a new tab
4. Drag the script off of your hard drive into the Extensions page and it will install.