Offtype is about as simple an online drawing application as there is.  There’s no need to register — just pick colors and draw.  You save your creation and can post its url address.

Of course, drawing by itself is not much of a language development activity.  However, if you look at this week’s list, The Best Art Websites For Learning English, I explained how I had students create collaborative stories where they used similar art applications to create illustrations for their sentences.

I’ve placed the link on my Examples of Student Work page under Student Collaborative Stories.  You can also find student examples of their stories there, too.