Best tool to create "Architecture Diagrams" (not UML)

I don't know if these diagrams have a specific name, I know them as layer diagrams since the describe the layers or stacks in the architecture.

You could create those diagrams in Visio - although I don't think there is a stencil that supports it directly. You could also try a number of other tools:

• http://www.lovelycharts.com/
• http://www.gliffy.com/
• Microsoft Word (has good diagram support in later versions)
• Paint.Net / GIMP

You can use whatever program you want as long as it can draw colored shapes.

Some people I know use PowerPoint, since you can make nice designs with it.

Or in Visio: New->General->Block Diagram. You can alter the design by right click->format->line. (You can make it more beautiful but I didn't want to spend to much time)

I don't know what they're called, but I've never seen one more complex than only a couple of items, so you'll probably get away with drawing them in Paint even without too much effort.