I've developed a Twitter application (the name of which I don't want to share publicly, I can share with few relevant members in PM though) that is used mainly by big accounts and currently counts over 1000 active users. The app has practically marketed itself through word of mouth since I haven't spent a cent in marketing. The first 2-3 people to use the app were a couple of socialites and from there the word spread like fire. Competition, as we speak, is close to null. Having invested a good amount of money in development and design I'm now trying to figure out a way to monetize on it. The application allows me, the owner, to post tweets/retweets from my users' accounts with an aggregate exposure of over 100 million followers. I can already monetize leveraging such feature but I think that would be bad for my brand (although partnering up with a platform offering high quality, spam free, viral content could be acceptable). I've also been advised to add a monthly fee, an option I like since it would help me not only recoup the initial investment but also cover maintenance costs (dedicated server, not negligible) and fund future upgrades (there have been 2 upgrades so far that brought 3 new unique features). Still, my priority right now is to build a strong user base and I'm afraid that adding a fee might slow the pace (user count has been more than doubling every month). Key to understanding this app is its target which consists of influential users or people with at least 10k followers on Twitter, they're the ones who need it and use it. Now I'd really appreciate your input pertaining business alternatives you think would be worth mulling on.