Seanau Icon Toolkit is an easy-to-use free icon editor.

At its simplest, you could use the program as a basic converter, opening an image in a regular format (GIF, JPG, PNG, BMP) and saving it as an ICO.

You could also use the drawing tools to create something from scratch, although these are relatively basic, just a few shapes with optional gradient/ radial fills.

What's more interesting is the Layers tool, which allows you to blend multiple icons together.

The Style menu changes the look of your icons with a click. Options include iOS, Origami, Mac, Vista and Crystal. Don't get excited, these don't do anything radical - sometimes they don't seem to do anything at all - but you can always undo the results if you disapprove.

There are some alternative Style options which might be more useful, like adding a reflection or a drop shadow, and your work can be further tuned with sliders for Hue, Saturation, Brightness and Contrast.