As a contributor to the Joomla community, CollectiveRay often releases free Joomla Extensions - Modules / Plugins / Templates and other development. These are available for free or for a minimal development support fee (the price of a beer or a coffee).
The way we do decide which Joomla modules and extensions to release works in the following way.
As we are creating a website for our needs or for the needs of our clients, we might find a deficiency of functionality, usability or find another reason why we're not happy with the way an extension we are using works.
At that point, we write our own Joomla module, to make sure that we are able to get the exact functionality that we need.
Once we're happy with the quality of the development, we release our new extension to the rest of the community. We will also typically submit the new module to the JED, such that it is easily accessible to anybody who needs.
Most of our released modules are free, though we do ask for a small donation, especially if you are using our work to make a profit. The donations are then used to fund the site, work and development of new extensions.