Guy Kawasaki gave an excellent keynote at the recent Experimental Marketing Summit where he spoke about the Art of Innovation. Yesterday he posted a link to the speech on Zentation - an innovative new site that synchronises video with PowerPoint slides.
Among the points Guy makes in the speech, he advises that you "don't let the bozos grind you down", using examples such as IBM's attitude to personal computers and Western Union's opinion of the telephone. For me this is the most important point made. No matter who tells you it won't work, or there's no market for it, you need to believe that you're right and they're wrong or you'll never get anywhere.
Predicting the future is impossible, creating the future is not! Now, go create.