I've been a coop member since it first came out. Recently I had some spare weight and started some virgin sites for the sole purpose of trying to measure the effect of the coop on SERPs for brand new domains and comparing the results with some other non-coop approaches. The results can pretty much be summed as "No surprises at all". Still, I figured that would seem too lame to post so here are some detailed results after a month: All Sites: - Domains registered within 30 days of July 16th, 2005 - Each site on a dedicated IP addresss - All use url rewriting to give all pages simple .html file extensions - They all have the same basic content just output in different formats - They compete in tier 1 category in terms of seo competiveness Sites A1, A2, C1 Specifics: - 3.5k unique pages Sites B1, B2 Specifics: - 52 unique pages Sites A1 & B1 Traffic Building: - 3k Coop weight starting 7/16 Sites C1 Traffic Building: - 15k Coop weight starting 7/16 Sites A2 & B2 Traffic Building: - 1 PR7, 2 PR6, 3 PR5, 4 PR4, 5 PR3, 6 PR2, 7 PR1 links from private network Results: - Indexing: All sites homepage indexed in all search engines in first week. All sites were fully indexed by G* and MSN within 2-3 weeks. Yahoo still has less than 100 pages from the A1, A2, C1 sites indexed. - SERPs: No site will display in G* top 500 results even for long tail search terms unless they are "quoted" even when the total number of matching documents drops to 5k. To put it simply: G* ignores all the sites. MSN on the other hand serves pages from all of the sites. It especially loves the larger sites on the long tail search terms as would be expected. Some of the coop weight on the B1 & B2 sites is pointed to subpages and MSN SERPs for the terms used in the anchor text yield some top 10 positions. Yahoo seems to have picked up on some long tail searches on the large sites but nearly as many (obviously, since it doesn't even have them indexed!). - Revenue: Not sure how I feel about including this and I think likely won't continue to do so, but for now, here's some info on it. The only revenue comes from adsense and it is derived 95% from A1, A2, C1 sites. Almost all the traffic is from MSN, though Yahoo does contribute a little. C1 is outperforming A1 and A2 by a margin of about 2 to 1. Total revenue has been averaging about $11/day for the past week or so. Unless something significant happens, I don't plan on updating this info for another month. Chachi also has experiments running but due to a screw up on my part, they only just got kicked off with coop weight and I'll leave it to him to post results whenever he feels there's something worth reporting.