Scale it by your user base-- that is, if your top user has 50k RSS subscribers, then make that the top of the scale. This makes it basically a percentile system

Scale it by your user base-- that is, if your top user has 50k RSS subscribers, then make that the top of the scale. This makes it basically a percentile system. However, I suggest not updating the coefficients in real-time. Otherwise you could have a new user join that instantly changes the scale. So calculate which user has the most Foo once a week or once a month to keep things a little more static. With respect to giving newbies an easier time, you could try using a log transform. This will give a quick rise in the beginning but saturate in the high levels. Try something like: log(X)/log(N) where X are the number of quanta that the user has achieved with a service e.g. number of Twitter followers and N is the maximum achieved by any user with that service. Then you could combine the services as grandalf describes above.