I found about about a great site the other day when I was browsing the internet - and a wonderful little resource ScribblerToo. It is immediately addicting, and with it one can produce all kinds of unique designs.
While it is somewhat difficult to draw with a mouse (as I do not yet own a tablet of any kind) I certainly had a lot of fun doodling Doctor McCoy, Kirk, and Spock: (to enlarge, right click and open in new tab or window)
I really enjoy how McCoy and Spock turned out - they are very strange. Kirk (with his super-awesome fatshirt) looks entirely wrong to me, however. That must be why Spock is looking at him so.
For anyone who is interested, I also have a DeviantART account here.