Simple stuff. They're great for decoration and details. Maybe during regular rounds as well; I don't see why not. Maybe sell specific ones in one of the prestige/grandmaster shops.
Example use of custom player heads: http://blocktopia.net/forum/threads/i-recently-bought-a-new-office.14168/
Example use of custom player heads: http://blocktopia.net/forum/threads/i-recently-bought-a-new-office.14168/