Display a list of a user's Organic Groups
You can use og_get_groups_by_user() for that.


  Get the group IDs of all the groups a user is an approved member of.


The API linked to above might be for OG 1.x, it's slightly different for OG 2.x.

 function og_get_groups_by_user($account = NULL, $group_type = NULL) {
 ...


For instance:

 global $user;
 $user_groups = og_get_groups_by_user($user, 'node');


The above example is not really great as $account defaults to current user and without $group_type you get all types of groups, not just node groups, but you get the general idea.