Do nothing? This isn't worth it.<p>Spend your time/money making an application that isn't so easily duplicated. You said it yourself that you weren't planning to make a mint on this. No point in dealing with the hassle of lawyers, paying the lawyers etc.<p>If you only had one competitor, it would be possible, but being that you have five competitors, and some of them are free, I'd have to say that the market is saturated and its time to get out anyway.