There's many business models surrounding FLOSS: support (pay for help, or additional features), premium (pay for more advanced software), hosting (pay for using the software on someone else's servers), donation (two versions of the same app, pay because you want to be nice to the developers), etc.
Not all of those business models align the interests of the developer and the customer/user in the same way: support-based models for example, benefit developers who introduce certain mistakes or delay introducing features. (In the short term. In the long run, it opens a door for competitors.)
What other business models have been successful for Open source software? Which of those align the interests of both? Are any of them morally questionable?