Depends. I was familiar with http://www.informatik.uni-trier.de/~ley/db/indices/a-tree/a/...
and to be successful, it has to be a great product.
I.e. find where the pain is and solve it.
Success lies on the product side, not the research...
Hmmm. But what do you think about those apps that I mentioned? They have pretty good algorithm inside, but are they great products?