Question: This question has always been around my head.

Can someone create a new product based on an existing open source project?

Say you want to create an "Apaxe webserver" that is basically Apache with your some extra plugins ( say support for ASP or something similar ) 

Is this possible?

Would you be able to create a closed source product ( either free or licensed ) 

As for GPL seems clear it is not possible because the source should be open. But what about Apache license, BSD and others "corporate friendly"

Are the price ( free for most of the project ) , bug fixes and counting with the core development team the only thing that prevent from others to commercialize those OS products?

What about: Khrome a commercial product based on Chrome with ActiveX support ( who would dare to do such a thing :P )

**EDIT**

Thank you all you all for your answers. 

So, again

***What prevents from similar ( clone ) products from appearing in the market?***

:) 

NOTE: I know we are not lawyers, and we could read every OSS license here <http://www.opensource.org/licenses>.

Answer: 
> 
> What prevents from similar ( clone ) products from appearing in the market?
> 
> 
> 

Nothing. The *real* question is: How can a similar cloned product get more popular than the original product?

Some cases where somebody might clone/fork a project:

* Picking up a dead open source project and continuing its development. If the new derived product is maintained regularly and it gets more updates than the original version, then people will start using the new version. This is one of the big benefits of open source - good software does not need to die, just because the original developers stop developing it, but someone else can continue from where they were left. One example of such a project (which I've used) is that the development of [Turck MMCache](http://turck-mmcache.sourceforge.net/index_old.html) had died out in 2003, so [eAccelerator](http://eaccelerator.net/) forked it and continued its development in 2004. I'm sure there are lots of other examples.
* There is a disagreement in the developer community of an open source project, and the project splits into two. That's why it's best to strive for a common understanding in open source projects, so that the community would not be split needlessly. If a project is split, the projects may continue living if they managed to attract enough developers and users, but otherwise they may slowly die. In general, splitting should be avoided, because it makes the community more fragmented and weaker. IIRC, in the video presentations of [Producing Open Source Software](http://producingoss.com/) (good stuff!) they mentioned a case where the original developer of some project wanted to take a completely new direction in the development, but the community of other developers wanted to keep the old direction. The result was that the original developer was kicked out of the project, so he created a fork of the project, while the rest of the community continued the development of the original project.
* A commercial closed source derivative of an open source project which was released under a permissive license (for example BSD). The derived product would need to be considerably better in features or in support than the original product. Otherwise people will prefer using the original open and free product.
Isn't that essentially what red hat does? Even though they have fedora, they are charging money for their linux distribution. Granted, they've written a lot of code for it, it's still based on open source-stuff.