Q:

How to make objects draw transparent/wireframe in the viewport?

I have several objects in my scene. I want all the objects to be visible so that I can see how they relate to one another, but I want to focus on just one. To do this, I'd like to make the other objects translucent and non-selectable. I know I can disable selection from the Blender outliner, but there doesn't seem to be an easy way to make just that object transparent. The reason I am trying to do this is simply so that I can see objects in my scene but focus on just the object I am editing.
I'm using glsl with mapcap for rendering and am mainly working in sculpt mode at the moment, and would like to stick with glsl if possible.

A:

You can make an object be displayed as a wireframe by setting the Maximum draw type to wire in Properties editor > Object > Display:

You make an object display as transparent by adjusting the alpha of it's material, and enabling Transparent in the display settings:

A:

This was the first Google result, and I came here looking for a Cycles answer but gandalf3's reply helped me realize.
First, on Material > Settings, change the alpha value (below Viewport Color)

Then, on Object > Display, make sure to check Transparency

For wireframe display it is the same method as gandalf3's answer.

