1. Begin with a new file, 300x300, and with #5D5D5D as your background color. Then create a new layer in the layers palette.
2. Now take the Rounded Rectangle Tool and create a similar shape to the one below, fill the shape with #444444. (Click for larger view)
3. Now head over to the layers palette and right click on layer 1, choose Blending Options and apply these settings.
Click OK, and now should you have something like this. (Click for larger view)
Then add some text, and maybe some inset lines, and you're done! This is what I came up with.
