The demo for Pokemon Omega Ruby & Alpha Sapphire holds a number of secrets. If you want a little extra challenge, you could seek out a secret mission in which you battle Team Aqau or Team Magma. But if you want to make some mad money, you might be interested in this recent discovery.
Yes, there is a second secret mission with a very low rate of occurrence. During this mission, you'll visit an island in search of a particular man who says he has an overabundance of Nuggets, chunks of gold that can be sold for thousands of Pokemon Dollars. He'll give you a Nugget, which can then be transfered to the final game. It's implied that you can later redo the mission and get even more Nuggets.
Pokemon Omega Ruby & Alpha Sapphire arrive for 3DS on November 21. There will also be a dual pack with both versions available.