I spent a few hours this morning playing around with a drawing application created by mysterious Internet personality, Mr. Doob. I liked it. It's an inspiring toy. Its simplicity and inherent limitations are its virtues. It'd be hard to create polished works with it but if you're in a slump and feeling uninspired an hour of doodling with it will probably plant some good ideas in your brain. I've always found an abstract sketch with a good title provides a solid foundation for a big idea mansion I can let my imagination roam around in later on.
Stretching My Leg
We Salute You Sirs
Roller Coaster Clouds
I like digital drawing tools for sketching ideas in color. This one's probably the best I've seen. Large powerful programs like Photoshop are too clunky and complex for brainstorming ideas. They give you too many choices, leaving you paralyzed with indecision.
The Web and Sketchy tools in this app are my favorites. They're dynamic like charcoal is. It's easy to get both light, midtone, and dark values quickly in a way that jittery hands like mine enjoy. Plus they make lines look organic and chaotic in a good way...
...but don't just take my word for it.