I've looked every where and I still don't see how weight is determined. I thought it was pages with ads on them, but that can't be right because according to google I have 300 and some, but my weight is only 5.
Maybe this should be in co-op forum, Anyway weight is determined by the number of pages google has indexed in their database and the PR of the homepage. Also you have the option of 1 to 5 ads which should give you more weight.
The number of pages in Google for the Coop is determined by the Google API, which is usually less than the number returned if you just do a 'site:mydomain.com' search from Google.com. The Google web site returns more of an estimate, the API filters out pages it thinks is similar and other things.