Tegaki Blog is a very well made picture diary blog with a focus on manga/anime type drawing. The drawing tool is easy to use and highly functional. Website has an English and Japanese version. You can get a widget to randomly show users drawings from the top page, or if you register, you automatically get code for your own page's art.

Just click on a pen and scribble away. When you want to start fresh, click on the text [描き直す]. Code is easy to spot on the widget's webpage.