I recently rediscovered charcoal. I love working with it. I had forgotten.
If you've never used it I highly recommend trying it. It's available at any art supply store and it's so easy to use. I love the ability you have to shade and really get your fingers dirty. I was introduced to the idea of adding white pain at the end to add highlights and I think it's brilliant, not to mention another opportunity to finger paint as an adult!
Below is a youtube video on the basics of getting started with charcoal.