[Osiris]

Source: Create your own file extension icons

I absolutely love all kinds of icons, and not long ago I found a very quick way to make my own simple Adobe-Suite-like icons. All you need is Adobe Air, and an app called Air Icon Generator. The app is from the same people who gave us Bookmarked Generator, and works with the same style, although with quite a bit more efficiency. You can churn out 4 different sized icons for as many formats as you want, I created about 10 in 2 minutes.
All you need to do, is fire up the application, select your style (Adobe style, or Web 2.0 star style), enter your text, up to four letters, select a background color and click generate. The shading is done extremely well, no matter what color you choose your icon will look good. This really is a great way to create file extension icons, especially if you use a lot like php, css, js and so on, you can get much better stuff the the original system ones.