Charcoal has been my friend lately. I don't remember when I first used it (probably Drawing I in college), but I just love it. For home studies I'll settle for a cheap-o ball point pen, a Sharpie, or litho crayon to avoid the mess, but for studio drawing few things make me happier than charcoal. Charcoal is immediate. It has the potential for great boldness and amazing subtlety. It's messy and it gets everywhere.
Speaking of framing... I'm looking for a corner vice and a V-nailer. Let a guy know if you have a line on one OR would like to go in on one (other Northland Studios residents, I'm looking in your direction). Otherwise I'm waiting for a good sale. This stuff ain't cheap.
Come visit Northland Studio most evenings and you'll find me there... hands blackened and face streaked like a kid playing happily in the dirt. You can join me. I've got paper and there's always more charcoal.