How to highlight a selected part of a scene?

[jwwalker]

I'm looking for ideas on how to highlight an object. In an OpenGL-based app, I've drawn a sort of halo around the object, by drawing the edges of the triangles with a line thickness and using the stencil buffer to mask out the object:

But it doesn't have to look like this, just some way to draw attention to a part without obscuring it.