A bit of background, I built the app because I was running an old Nexus One and the Facebook app was too large to install alongside my other "essential" apps (15mb at the time, its now 38mb!). So I spend about an hour or so and cobbled together the app.
For almost a year and a half it had less than 1000 installs and then in Feb this year it started to rapidly gain installs. It is currently sitting at 241,000 installs (with 55,000 active users).
I figure I should take advantage of this and figure out some way to monetize the app.
Unfortunately the app is all about size and trust (as it sandboxes the FB web app) so most of the ideas I've come up with don't seem to be in the spirit of the app.
Some of the ideas I've had:
* Put in ads and add an in-app purchase to turn them off
* Put in a "donation" in-app purchase
* Add support for other social networks but only enable them after an in-app purchase
The app also has some pretty interesting demographics. Most users are from non-English speaking countries: Turkey 18.14%, Philippines 8.38%, Mexico 7.46%, Morocco 6.52%, India 5.27%, Indonesia 4.10%, Brazil 4.04%, Thailand 2.72%, United States 2.59%, Colombia 2.44%, Others 38.33%
The app is called "Social Lite" see here for more info https://play.google.com/store/apps/details?id=com.rabidgremlin.sociallite
My current go-forward plan is put a survey in place and poll the users on what they want and what they would pay for
Use it as a fun experiment to see how much you can grow it not how much you can monetize. Formulate some assumptions and test them. I'd personally pick one of the countries and see if I can push installs in that country hard (might be difficult due to language issues). Try to figure out how people learn about your app and install it. Figure out what phones it is installed on and write a blogpost on using your app on that phone etc.
55k active users isn't bad. If you keep on growing someone will get interested even if you didn't monetize before (possibly even because you didn't) especially since it's not a "fad app" but something sustainable as long as there's low resource phones. [worst case you can use it if you ever want to apply at Facebook]
tl;dr: use it as your private growth-lab and learn a lot :)