Well, I will tell one relevant problem that can be annihilated with this: ads placement. Google advertisement adwords is all based on a auction mechanism at the end of which you have to find the best allocation of ads to bidders (to slots) - which has an evident combinatorial nature, to find optimum you should try all possibile combinations. This is typically solved in approximated ways. It may not be a "conventional quantum computer" but it's pretty usefull anyway:) I can't wait to toy with one..