The obvious alternative is porn. But I doubt it will work, unless you aim specificly at current Bitcoin users. And even then there are much more people who own a creditcard. You run into this problem for most applications. I'd like to see the big Chinese webshops accessible through Bitcoin, but the market is just too small to be worth it.
Another alternative, but they exist already, is a payment processor. This takes the hassle from the webshop, and allows the customer to pay with Bitcoins. You could argue this is an exchange, which you don't want.

Chopcoin tried to make a "Bitcoin agar", and although Agar itself is very popular, the userbase is just too small. Games will have that problem too. Unless it's turns out to be really big, in which case you're doing yourself short by limiting it to Bitcoin.