So, there is no Visio for Mac now.

But don’t lose your heart! There is a way to share your Visio documents on Mac. To work with MS Visio documents on Mac you can use alternative software. You need to save your Visio document as *.vdx file (in Visio XML format) and find any diagramming software which works in Mac OS X and supports import of Visio XML files.

For example, you can use ConceptDraw Professional which is crossplatform (works both in MS Windows and Mac OS X) and supports import from and export to Visio XML. So you have an ability to work with Visio XML files on Mac just as with regular documents.

If you already have a vsd file and you don’t have a Visio installed you can use the free of charge Visio files converter.

Use the standart Open dialog to import your Visio XML file into ConceptDraw then save it as regular conceptDraw document and work with this document in Mac OS X as well as in MS Windows.

Each shape is represented both in Metric format of dimensions and in US (inches) format.
Many of such ready shapes have unique features added with using of formulas of internal Visio programming language. For example, they can automatically stretch to fit some area or text. Despite the fact that Visio have lots stencils with shapes they are black-and-white in most cases.

So if you want to create a diagram with lots of color shapes, you need to find something else.
ConceptDraw is an alternative for Visio both on PC and Mac and in contrast to Visio ConceptDraw has a set of libraries (analog of Visio stencils) with beatiful coloured shapes. This distinction is especially noticeable in ConceptDraw libraries and Visio stencils assigned for Landscape design.

ConceptDraw shapes also supports formulas and custom properties for all shapes. ConceptDraw uses its own internal CDBasic for formulas. So you can import Visio shapes to ConceptDraw and export ConceptDraw shapes to Visio but all “smart” properties given by formulas will be lost.