I really love the projects over at Art House Co-op. Lots of people do the Sketchbook Project, which is a serious commitment if you ask me, but they often have more specific, creative prompts with quick deadlines over on their projects page.
Sometimes you just need a little nudging. This submission was for their Infinite Scroll Project, where they will collect these images into a long collaborative piece. Really neat. The theme for this one was “Patterns.”