With both a select menu dropdown or quick search filtering options, your users will be able to find the forum they want quickly and create a thread in one action. A button call to action will be displayed on every page so it is easily accessible at any time. The call to action button on every page easily allows users to post a new thread from anywhere on your site. You're able to whitelist nodes so that only certain nodes are able to show up in the filter and blacklist nodes you'd prefer not to show. You can choose to display a filter list or a select menu. You also have the option to hide the trigger from users in nodes where they do not have appropriate permissions to make posts. Your call to action button is customizable and can be changed to say something other than "Post New Thread".