Xoops France Site co-webmasters (Xtremdj and Pascal) released a great hack to improve the referencement of a Xoops Site in Search Engines (notably in Google). It is inspired by the PostNuke "article.php" file working. It puts all the article words in the meta keywords of the page , separated by a comma and adds the news title after the site title.
Xtremdj released first a rc1 version and Pascal modified it for rc2 version... (For example: xtremdj had 20 Google references each day before hacking, now he has about 200 per day)