I have an idea, what if I add to the meta tags the forum title as well as few forum threads? In this way every page will have different tags... So the search engines will have even a better variety of words for each page...
Also I just found out that, according to the new crawling rules, is recommended NOT to separate the meta keywords by commas????

Normally keywords in meta tags are separated by commas. Comma is take as "Or" while space is taken as "And". However there is some evidence that when keywords are separated by a space the search engines make their own combination of keyword by itself.
LINK:
http://www.webdesigns2000.com/WebPage1/metatags.htm
It will be even easier to make the mod then...