Open Peeps - A hand-drawn illustration library.
Typora - A minimal Markdown reading & writing app.
Control Illustrations - 108 free flat illustrations with customizable characters
Dillinger - joemccann has 95 repositories available. Follow their code on GitHub.
DrawKit - MIT licensed SVG illustrations, in 2 styles
StackEdit - Full-featured, open-source Markdown editor based on PageDown, the Markdown library used by Stack Overflow and the other Stack Exchange sites.