Slick Black Interface Button:
Create a new document (300x300)
Using the rectangular marquee tool, make a selection within the canvas, and fill it with black.

Now bring up your layer styles for that layer. And use these settings.
Inner Shadow: (Use Default Settings)
Gradient Overlay:

Stroke:

And it should look something like this when your done.

Now, its time to add some gloss to it.
Create a new layer (Layer > New Layer)
Now, Ctrl+Click the button layer, (this should make a selection around it.) Now, using the “Elliptical Marquee Tool” and holding “Alt” Make a oval selection around the bottom half of the button. It should now look something like this,

Now (with your top layer selected) fill the selection with white. And drop the opacity down to about 20%. And your final result should look something like this!

These buttons on a Nav Bar:

© 2006 Scott Walker
Enjoy!
-Scott