For my goals, the query "phpbb spam" should return Textual Confirmation and Links Rejector tools on the first page. No luck so far, but I managed a nice trick to get there indirectly:
Some time ago, Lauri Harpf (A Promotion Guide) published a nice article "How to stop spam on your phpBB forum", in which he pitched the tools.
I announced the article in the bbAntiSpam forum and the blog "Spam Bots and CAPTCHAs".
In a week, the article appeared on the Google's first page.