Bases on an article I found at SpeckyBoy that features 28 Excellent Free Mac Applications for Web and Graphic Designers I´ve select 10 of those apps to present it to you base on the ones that really seem more interesting and usefull. By the way this is the first of the articles I´ll be writing in english, so here we go with the top ten:

Gimp

This is my firs app in the list, GIMP is a freely distributed piece of software suitable for photo retouching, image composition, and image authoring. It can be used as a simple paint program, an expert-quality photo-retouching program, an online batch-processing system, a mass production image renderer, or an image-format converter. GIMP is modular, expandable, and extensible. It has a lot of plugins avaliable. There is another app to be used as an alternative to GIMP and X11 motor: Seashore Explorer.

Overview and Download: GIMP Homepage.

Scribus

Scribus is a a open-source program that brings professional page layout design such as a magazine. Scribus supports professional publishing features, such as CMYK color, separations, ICC color management and versatile PDF creation. Definitly, a powerful tool to write a paper.

Overview: Scribus Homepage.
Download: Scribus Download Page.

Google SketchUp

As a future architect I´ll been using Google SketchUp a lot this days. For those who doesn´t know what is this app about here you have a small description of this amazing software developed by Google. SketchUp is powerful yet easy-to-learn 3D software. SketchUp is used by professionals and consumers alike. It contains a unique interface that allows 3D forms to be created, viewed, and modified quickly and easily. The core of its simplicity is that you draw the edges of the desired model in 3D space, just as you would using a pencil and paper. SketchUp infers your design intent and automatically determines the nature of the lines and fill shapes to create 3D geometry. There is a Windows version also.

Overview: Google SketchUp Homepage.
Download: Google SketchUp Download Page.

Lego Digital Designer

Once I was talking with my father that I´ll be great to design some churches of El Salvador and make them real through LEGO´s. So I start to research over the internet and I found Lego Digital Designer that allow me to build my own designs and ask the pieces to build it myself. 

Overview: Lego Digital Designer Homepage.
Download: Lego Digital Designer Download Page.

Autodesk Maya

Maya Personal Learning Edition (PLE) is a special version of Autodesk Maya software, which provides free access to Maya for non-commercial use. It gives 3D graphics and animation students, industry professionals, and those interested in breaking into the world of computer graphics an opportunity to explore most aspects of the Autodesk Maya Complete software in a non-commercial capacity.

Overview: Autodesk Maya Homepage.
Download: Autodesk Maya Download Page.

Graphisoft ArchiCAD

In Mac we can´t run AutoCAd, but we have ArchiCAd that delivers new and enriched capabilities designed to help architects develop their concepts, compete for business more effectively and boost business efficiency. The enhancements reinforce ArchiCAD as an extraordinarily powerful design tool for architectural practices – large and small – worldwide. This is a must-have for architects running OS X.

Overview: Graphisoft ArchiCAD Homepage.
Download: Graphisoft ArchiCAD Download Page.

Blender

Blender is the open-source software for 3D modeling, animation, rendering, post-production, interactive creation and playback. It is available for all major operating systems under the GNU General Public License. Version 2.44 offers numerous bug fixes. Version 2.46 includes cloth and fur simulation, physics caching and baking, shading, glossy reflection and refraction, raytraced soft shadows, improved rendering features, and more. Personaly I´ve never used Blender, but it is in my list of programs to test.

Overview: Blender Homepage.
Download: Blender Download Page.

DAZ Studio

DAZ Studio is a feature rich 3D figure posing and animation tool that enables users of any skill level to easily create stunning digital imagery. Whether youre a 3D newbie or an avid 3D artist, you’ll find DAZ Studio is the perfect tool for designing unique digital art and animation with virtual people, animals, props, vehicles, backgrounds and more. 

Overview: DAZ Studio Homepage.
Download: DAZ Studio Download Page.

Comipro Plus

Have you ever want to design your own comics? This is you opportunity with Comipro Plus, which compiles the document with the word processor as the material using the picture and the photograph. 

Overview: Comipro Plus Homepage.

Bryce

Create breathtaking realistic 3D landscapes and animations with DAZ 3D Bryce 5.5. The easy user interface simplifies the design process for a novice or the seasoned professional. Start out building or importing a landscape as impressive as the Grand Canyon. Populate it with buildings, people or any other object you create or from the extensive DAZ 3D library. The Light Lab provides you robust control over your sunsets, moonlight nights or high-noon ambiance. Tree Lab allows you to plant your landscape like the gardens of Versailles. As I said before, this is a software to be test as soon as I have time.

Overview and Download: Bryce Homepage.

I hope you´ve like this article base on SpeckyBoy´s one.