In its first few years, my webgame had donations flowing in at the rate of about 50 cent per active player-year. By that I mean, a population of 100 active play

In its first few years, my webgame had donations flowing in at the rate of about 50 cent per active player-year. By that I mean, a population of 100 active players (active means using the website at least once per week) would result in some 50 dollars per year. It's a lot less now due to less activity on my part. This is in the same order of magnitude as adsense, except that adsense depends less on "fresh" users. This is all small numbers though, since my game inherently doesn't scale.