For my forumdisplay pages I don't mind using the forum description as the description. But for each showthread page I can't find a way to include a dynmaically generated meaningful description and keywords.
What would be nice would be to pull so many characters of the first post as the meta description for the showthread pages. Including a meta description tag generated from the text of the thread would help some search engines to include a better descriptoin rather than text like "click here for your user cp, click here to register, click here to search the forums" as the description for any threads they list.