Mind Hive: Several – arguably, most people qualify as at least a mild form of this, since the habit of running a muse, a personal assistant AI, on your implanted headware is close to ubiquitous. Of course, actions aren’t by consensus in that case, but the habit of turning your body over to said AI for boring maintenance-type functions while you go do something more interesting in virtuality is also close to ubiquitous, so.
But there are more than a few mental architectures that work this way deliberately, especially among native infomorphs that use ‘shells only for specific tasks and so tend to have them run by consensus of a team of specialists, rather than assuming that one-shell-per-process is “natural”. And even relatively simple high-coordination AIs have multiple consciousness loops/narrative threads in order to multitask effectively, whereas most biosapiences only have one; of course, they share all data in real-time, so may not quite qualify.
And, of course, the “Ocean of Mind” of the Transcend is a functional soup made up of teleological threads derived from aspects of the transcended hyperconsciousness, the uploaded personalities of the dead, and instantiated expediters based on local entelechical maxima. Thus, arguably, the Hive Mind is also the biggest Mind Hive of them all.