What Kind Of Software is Best For Illustration?

[Pieter]

http://mypaint.intilinux.com/

This is a great little app for painting, it's still very much in development. You can't do stuff like custom dabs but the basic round brush is incredibly customizable, much more then in Painter or Photoshop. It also extends the canvas automatically, so you'll never run out of space.
You can for instance change the hardness or squeeze based on pen pressure, scattering on speed of the stroke, etc.
And every setting comes with a pressure curve, so you can get allot of effects out of the basic round brush.

[Kamikengen]

Depends entirely on the style of illustration you want. What do you have in mind?

Adobe Photoshop (raster) and Illustrator (vector) are good all-around packages. Flash is good for freehand drawing vector.
Then there are digital painting packages that aim to be close to the real thing. Corel Painter and Abmient Design Artrage for instance.

I personally can't go without Photoshop anymore, it has a wide array of image editing possiblities, vector paths and a brush engine you can use to paint with.

I use PS CS4 mostly, but I go without a graphics tablet... I don't have a job, so the money doesn't come that often.

Now I have to use a school laptop, and it only has PS Elements 7. It pisses me off, because it isn't nearly as powerful as CS4, and that's what I'm used to.

Another one I found really good was PS CS3. I know it's older, but in my opinion it's better laid out.