Successful examples tend to be revenue models where what you pay for is support. While that does technically generate revenue (and potentially lots of it) it i

Successful examples tend to be revenue models where what you pay for is support. While that does technically generate revenue (and potentially lots of it) it is not generally applicable to many open source projects particularly those not large enough or foundational enough to even raise the interest of paid corporate support. At the moment that would leave donations as the rev stream and I guess that might work for some. The other model that can work is one where you offer a basic open source product but then charge for a closed source "professional version". I guess, I wonder if that type of thing is is really open source in the end.