I have a small iPhone app that generates around 200 a month. Nothing spectacular but not bad for a bit extra.
I always thought that building something like this might generate an initial income (and potentially a profit) but that consistent, longer-term revenue was much harder to come by. Any chance you'd expand on what your app does and what the revenue generation/ongoing promotion model is?
You can do reasonably well (if you're just after pocket change) with a decent utility app - let's be honest, most of them have shockingly bad UX, and reap ad revenue.