With the latest Steam update, Community Groups can now Curate their own Steam storefronts. You don't get anything for this, but you can follow stores that offer things that interest you from your own Steam account.
I've created the NOR Curated storefront, it currently includes 25 games covering MMOs where we have branches (Rift, ESO, etc) and other co-operative games that members have mentioned on this forum previously. It doesn't update immediately upon adding recommendations, so you may see fewer than the 25 for a bit.
If you know of an MMO or Co-op game I should add, let me know. You can follow the store at the link above. Just click the Follow button while logged into your Steam account. Also, if you haven't joined our Steam group yet, just let me know your Steam username, and I'll friend you and send you an invite.
Thanks!