Simply make the Faucet pay out less, let's say 0.01, also have a regular monthly top up of 1 to 10 BTC that's a 1000 freebies per month, when it's gone it's gone.
Check IP Address, Catchpa and yes Advertising.
Add a paypal button there so people can transfer funds from their paypal account into BTC's, all of the above.
Put a Paypal or other such donate button there. The only reason I wanted to use the Faucet was to see if I got something in my wallet, even if it was only 0.001 BTC, people can't expect significant amounts of Free money, that's not Free market capitalism.
The purpose of the Faucet should be to help demonstrate the technology, if it's about giving people free money then then it will never be sustainable because in order to give some one a significant amount of free money it would have to be at least 1 BTC which is simply not sustainable.
If you offer 1BTC or more most of the people who arrive will be out to 'steal' the money, if you make it 0.001 and make it reasonably fiddly to get at then most of those who bother are more likely putting in the effort for a few pennies because they want to see the technology work.