Go to ChangeThis. The mission of ChangeThis "to support and spread great ideas." And they accomplish this by sharing proposals and manifestos from some of today's top thinkers and leaders.
|How To Be Creative by Hugh MacLeod at ChangeThis|
Don't be intimidated by that. The ideas are presented in concise, attractively packaged pdf presentations, short enough to read on the fly, but involved enough to actually challenge your thinking. Think TED Talks on paper.
Some of my favorites: