Ink wash is one of the coolest mediums to work in, and, for me, was the perfect transition between pencil drawing and painting. it's still black and white, allowing you to focus on one color gradation, but you can't erase. (Technically, you could scrape some paper off with an electric eraser, but only if you have premo paper that won't fray.
This is an ink drawing I did in my Drawing II class a couple years ago. It was done using quill and ink. (Yes, that still exists.) We had to set up our own still life using 3-5 different items. My items were a mod photo album, a dried rose, and a black beaded necklace. When using quill and ink, you learn to use different nibs which control the amount of ink that is going to flow onto the paper. You also learn different techniques. Probably the most familiar would be pointillism which I used for the shadowing. I can't really remember what the other techniques were called, but basically that build different textures that allow the stem and petals of the rose to look three-dimensional and that allow the beads on the necklace to look like light is reflecting off of them.
This is something I made up when I was bored one day and found all of my old ink wash utensils. Instead of using the full concentration of the ink, I watered it down and used a really loose nib that allows a lot of medium to flow onto the paper. Then, when the ink was semi-dry I went over it with a wet paint brush and smudged some of the lines so make it look more abstract and add some depth. When the sun image had completely dried, I wrote the lettering using the quill and a tighter nib.
This piece was also done in drawing II using only pure ink wash techniques. The ink was always watered down and mostly added to the paper with a paintbrush instead of a quill and nib. This is the closest I got to actual painting for a long time. After all the ink was added to the paper, I went over the darkest parts with charcoal in order to add a bit more drama to the piece.