Sketchpad Escape is a freemium screen saver application that displays selected black-and-white sketches by Roger "Rog" Coe against colorful backgrounds. The time interval of image change is customizable, from 10 to 60 seconds, as is the time until activation, from 30 seconds to an hour.
The application is quite unusual among Mac OS X screen savers in that it runs independently from System Preferences' Desktop & Screen Saver pane, where built-in screen savers reside and where most third-party screen savers integrate themselves. Because of this, one must disable the System Preferences screen saver for Sketchpad Escape to function without being overridden.
There are currently three purchasable features to this application: the ability to display the current time, the ability to customize background colors, and the addition of more doodles. The screen saver is perfectly nice to look at without these features, with a preselected background color palette and high-resolution, alpha-layered foreground images.
Sam's Relevant Factoid: When I've had to sort through my class notes from school years long past, I often find my doodles more valuable to keep than my actual notes!