1) Create a new document (or use the workspace you want the shape to be added to.
2) Select the shape tool you wish to use. Most people want a hollow rectangle (i.e. rectangle tool), but this works with any of the shapes: Hollow rounded rectangle, hollow circle, hollow ellipse, etc. Even hollow lines (but those are effectively rotated rectangles). You get the idea.
3) Draw the shape on the canvas. A new shape object should be added to the layers palette.
4) Double-click the shape object in the layers palette to open the "Layer Style" window.
5) On the "Blending Options" page, change the "Advanced Blending"'s "Fill Opacity" to 0%.
6) Next, go to the "Stroke" page. If preview is enabled, you should see what I'm getting at by this point. Anyway, change the color and size or use a pattern or whatever. Inside and outside strokes usually look best - especially if you used "Snap To Pixels" in the "
There. You have a hollow shape that is a vector object (more or less). Unfortunately, scaling the image doesn't scale Layer Styles accordingly, so you have to rasterize or fiddle with it, but it is better than trying to eyeball two of the same object. Wish I had figured this trick out for the VerifyMyPC logo artwork. It wouldn't look quite so silly with the bulging inner corners.
Oh well. Hopefully this tip saves someone some effort. Leave a comment if it helps you.