I have installed a new plugin to this forum which makes it possible to add a [HASH]hashtag to a post which will then automatically be turned into a link to the search for this hashtag. There will also appear a Tag-Cloud at the bottom of each forum for easy navigation to hashtags.
The way to use this is to write: [#]tagname ... to create a new hashtag. It is important to use the opening [ and closing ] brackets.
Please try it out and let me know what you think of this feature.