You get pics from the minigames, including the best friends'. You get the 18 BF pics from the last 6 minigames (the first is Terrence the terrible, it is in the foster home's games room).
Here is a post with a list of the minigames and the pics that you can get from each one:
http://www.fosters-home.com/forum/showthread.php?t=2382