My thoughts exactly. Doesn't anyone want to innovate, or "change the world" anymore? If someone's going to go through all of the labor to make a copy of groupon or an iFart app or a twitter API mashup just for the cash, they should just write a Forex trading algorithm. They'll make more money that way, and their models will be infinitely more computationally unique than any consumer copycat.
You mean writing one that makes money? That's infinitely harder than the examples you provided.
Quite a lot of smart guys put nontrivial effort into that. You need to be as good as them, preferably even a little better. Good luck.