it's interesting that in recent years quite a few open source projects have been very smart in securing complete financial funding from one or two big commercial vendors who use their stuff.
and companies like TrollTech who make Qt, are getting rich off their dual open-source - commercial license.
although i'm not all that fond of TrollTech, i think the dual license model has real appeal from an ethical standpoint - those who use something to make money from it must compensat developers; those who use it in free work can use it freely.
the only thing about these models is that they tend to work for only a very few open source projects which have big companies willing to fund them.
i think the second route to providing open source authors with some reasonable compensation would be the move in this society towards more ready donating by users to support the work. if people got into the habbit of making small donations, it would be enough to support independent coders, writers, musicians, etc., who really aren't motivated by the idea of getting rich, but would just like to be able to do good work and get enough to survive.
