Pen & Ink and Digital Artwork
As I'm writing this, it's been about a year since I did any regular drawing with traditional materials (paper, ink). I've really enjoyed working with my Wacom tablet in Sketchbook Pro. It's a very natural and intuitive system and I find it's just faster to do a quick sketch using the tablet and software than getting out the big art materials bin and some drawing paper (not to mention the cleanup)! The other big advantage is that I would often have to scan my artwork in order to share it with people. Now, it's already in digital form, which saves even more time.
Having a tablet has come in handy in all sorts of non-art situations, too. I annotate documents and screenshots with it all the time. Also, with PDF Annotator, I've even started digitally signing PDF documents (this was a huge sanity saver when purchasing a new house)!