Some of the most popular faucets right now are the ones produced by a member of these forums named
donaldcoin. In a couple of his sites, he allows for users to upgrade within the faucet. What kind of upgrades are you looking for? I'll give you some of his sites examples:
DonaldCoin:
http://donaldcoin.comFirst of all, he offers "Free Upgrades" that don't require a deposit; you can use your in-game balance in order to upgrade between the two types of generators that he has
Secondly, he offers "Premium Upgrades", which require a deposit in order to upgrade your generator.
Is this what you're looking for? If not, he also has a site called
HitPxl, which has just one upgrade available... Again, this one requires a deposit:
And lastly, he has a brand new site called
Hotel BTC, which allows for upgrades using your in-game balance; deposits are not allowed here.
Is this what you're looking for? If so, contact donaldcoin and see if he can help point you in the right direction. He may not be free, but he's probably one of the top faucet admins that can help direct you with where you need to be.
Otherwise, if you're talking about starting an "investment" site that "doubles" people's money... then please don't do it. You'll get shit on by the community here.