I've begun creating Artist Trading Cards (or ATC) on a whim after reading up about them on the net. What I love about them is that I can enjoy doing them with my daughter (Nana). They are small enough that you can complete one in a reasonable amount of time and they work well with the attention span of a 6 year old.
Here is a series I did, completely inspired by Nana who told me I should do drawings of her stuffed animals. Watercolor, pencil, marker on 80 lb card stock.