Alot of artists are doing some great works on trading cards and mini two x two inch canvases. I have a very good friend that this is all she works on. And I was so impressed that I had to try a few myself. I found out that they are not any quicker than larger works. But, do cause for some very tight work. Here is my sample.
I suggest that you should try just to see what you can do. And it provides a great outlet, as well as can get.your creative juices flowing.