Simply putting up some ads in your app is unlikely to do much for you. A few months ago, Valleywag reported on a group that found 0.04% clickthrough rates to b

Simply putting up some ads in your app is unlikely to do much for you. A few months ago, Valleywag reported on a group that found 0.04% clickthrough rates to be common for ads on Facebook. That's 400 clicks for every million impressions. Not good. Your best bet is finding some highly effective way to target your ads (maybe by letting a third-party company serve them), or use your FB app as a loss leader for something else.