Creating a cool left navigation panel

Start by creating an ellipse using elliptical shape tool.

Select direct selection tool and select the elliptical path. Duplicate the path. Press Ctrl+T and scale down the duplicate path.
Enable subtract form shape area form the top bar.

With subtract form shape area still enabled on top bar, create a rectangular path over the elliptical ring.
Apply layer styles as shown below.

Create a rounded rectangle for the button and duplicate it four times.
Copy the layer style from the elliptical ring and paste on button shapes.
Duplicate the button shape of the top button and scale down. Remove layer style from this shape.
Apply following layer style.

 

Duplicate this shape. Remove layer style from this shape. Rasterize the shape. Fill with black to white gradient.
Change layer mode to screen.
Duplicate the blue button and place on the other buttons.
Create two small circles and apply the same layer style we used for the elliptical ring. Fill the background with dark gray color.
Type button links with a nice font.