I think your definitely thinking along the right lines Rhiana. Stickiness is a combination of things among which can be unique coding, but more towards unique content that is filling a need or want.
If you are to able to do as you say and create this kind of unique experience using free scripts and knowledge gleaned from self-learning - definitely go for it.
Just make sure you're not adding something that seems too cookie cutter in nature. Think about whether you would enjoy it if you were using the app for the first time. Is it entertaining? Informative? Funny? etc.. Has it been done before? and if so, are you improving on it?
Keep thinking along these lines and building content(applications included) that is unique, fun and exciting, and how can you go wrong? The viral effect is a funny thing to hunt, but if you hit the right combination of factors, it can't be beat for exposure.