SEO for phpBB / Google

allinurl:http://www.site.com lists pages that have http://www.site.com in the url. Obvioulsy that is mostly you own pages, but there will be a few directory-type sites that have stuff like http://www.othersite.com/www.site.com/

It’s not a particularly useful command.
allinurl:http://www.site.com site:http://www.site.com will list your own pages,
but so will
site:site.com

Also
“+http://www.site.+com“
will list the pages that have your URL on them in the text, which is a little more useful than the first allinurl use above.