Step 1:  Create a blank 200px by 200px document and Edit > Fill it with 50% Grey. Now run Filter > Noise > Add Noise, with the amount set to 20%, distribution set to uniform, and monochromatic checked.

NB.  You can set the amount higher if you want a coarser grain, or lower if you are going for a more subtle effect.

Step 2: Now brush that metal by selecting Filter > Blur > Motion Blur, with the angle set to -45 degrees, and the distance set to 20px.

Step 3: Its a little plain, so add a couple of highlights using Filter > Render > Lighting Effects with the following settings:

Light Type: Omni
Intensity: 21
Light Colour: #FFFFFF
Gloss: 100
Material: 100
Exposure: 0
Ambience: 10

Step 4: And there you have it - a brushed metal texture that you will find useful again and again.

NB. Feel free to fiddle with the settings in steps 1, 2 and 3 until they suit your own personal tastes. You can also build up layers of metal textures to create some truly unique effects.

Variations: You should, of course, use this texture as a starting point for more complex creations. The sphere on the left, for example, is a blend of the metal texture, with a Shiny Sphere.  You can also learn more about object textures with my texture mapping tutorial.