Xan,
welcome to KivaFriends - IMHO you have posted in exactly the right forum...
Many of Kiva's Field Partners hand out loans to "groups" of borrowers, quite often members of village banks or similar associations. You can usually spot these loans by looking at the borrowers' photos - or by entering "Group" as search term on
http://www.kiva.org/app.php?page=businesses. I am not sure, though, how many of these groups really are "coops" in the sense you are using this term.
Just to mention it: One of Kiva's Field Partners is organized as a "coop": Paglaum Multi-Purpose Cooperative (PMPC), Philippines -
http://www.kiva.org/about/aboutPartner?id=126Best wishes,
Wolfgang.