I could not find this spreadsheet in any other thread here, so I thought to revive it.
Newcomers might even not be aware of its existence (be aware young Padawans, its name is misleading , it was made by the former PT community, not by the owners of the site)
I myself am looking especially for PSN friends, but also Steam, and Nintendo.
Left to be said, that the Gamecenter list is not of much use anymore (correct me if I’m wrong). No good solution for it as for now.