Written by Mat Dwyer Created: October 5th, 2004
I made all these icons when I was just learning PS a while ago, so I thought I'd do a tut on them. Most will be similar, but to start off here is the Maximise button. I'll also do one for the start bar, a window, even the windows logo (swish intergrated for ease of use).
Here is the image you are making:

Maximize
1) Open a new Document, 97x97. Have your forground color the color you want the button to be.
2) Take out the Rounded Rectangle Tool.
a) Draw a rectangle so it fills the whole thing, with about 2 pixels empty all the way around.
3) Make a new layer. Take out the Polygon lasso tool and make a selection the same as the maximse button. (Easiest way is to make a rectangle, then just delete another rectangle near the bottom)
4) Add an outer glow to the new layer with the settings:
Color - "#FFFFFF"
Size - "8"
5) Go into layer style for the rounded rectangle.
Drop Shadow:
Opacity: 100%
Distance: 4
Size: 5
Inner Glow
Color - "#FFFFFF"
Size - 13
Bevel and Emboss

Gradient Overlay
Click to view attachment
Stroke:
Color - "#FFFFFFF"
Size: 1
Here is the minimize button:

The only difference here is draw a line thats straight near the bottom thats fairly thick. Refer to your own minimize button for more details.
Here is the X button.

Make your forground color a darker red.
Type an "X" with your favourite sans like font. You may have to rasterize it so you can stretch it using free control (Ctrl+T)