Here's a highly inspirational blog called Doodlers Anonymous. It's frequently updated with sketches from from doodlers all over the world.

From their About page:

Doodlers Anonymous was founded to celebrate our addiction, and like any other, we're hooked. The need to draw, sketch, and doodle is constant. We doodle on almost anything we can find — pencil in a moleskine, marker on a napkin, ink on a torn receipt, sharpie on concrete. And we do it habitually — while on hold, in a meeting, during class, or while we should be sleeping.

This is a permanent home for spontaneous art. There's a blog, interviews, themed-submissions and a lot of amusing thoughts on paper.

You can find the blog at doodlersanonymous.com.