Not so much minigames, but other activities that are done in PnP during camp as opposed to while adventuring. A perfect example would the wizard's spell copying. That takes a few hours per spell lvl (personally, I do 1 hour per spell lvl when I DM, but that's just me), so have any spell copy work done then.
Have crafting. Toolkits in PnP, like alchemy, herbalism, poisoner's kit, or smithing kit. Have the characters work on individual projects like making potions, making armor and weapons, or even crafting scrolls during this time. The more complex, the longer it would take (in the form of in game days). I understand that potions and such are relatively easily accessible in game, but the idea of being able to make such gear is appealing to me. Think about it, a rogue who is able to make his own poisons, and different kinds of poisons for that matter.
