I came across this really fun idea over at Design Sponge called The Sketchbook Project. Started by The Brooklyn Art Library, it's a collaboration of sketches from people all over the world, (including you!).
One signs up on the website for a certain theme, and then gets a moleskin sketchbook (unfortunately it's $25) that you fill up with doodles and sketches based on the theme you chose. The book are compiled together and displayed at various galleries all over the country.
Sounds pretty cool to me! For more info, head to the Sketchbook Project's website. I'm considering ponying up the 25 bucks to participate. I'll let you know if/when I do.