As some users have experienced, there is potential to receive a candy of the type corresponding to a Pokémon you feed in any of your team's gyms. This is especially useful to players who haven't been able to amass enough candy to evolve their Chansey or Dratini yet.
I have yet to personally get any candy this way, though, so this is clearly not a guarantee. What is the chance that I get a candy as a bonus for feeding a Pokémon in a gym?