Are you looking for a free, open alternative for iTunes, Dreamweaver or Photoshop? Just have a look at the open source as alternative / osalt website: there you look up the commercial product, then osalt will guide you to a catalogue of alternatives, all free open source projects.
The why of open source software, from their website
"By choosing an open source product, the user obtains a number of advantages compared to commercial products. Besides the fact that open source is always available for free, it is a transparent application, in that you are invited exclusively behind the scenes to view all source code and thereby to suggest improvements to the product. Furthermore, every product is covered by a large dedicated network, or community, who is more than willing to answer any questions, you may have."