Creative ideas may seem to come out of nowhere but actually a new idea usually is a combination of existing factors. You need some kind of stimulus to prompt your new idea and with the internet you have more information coming at you than ever before.
In the Huffington Post, Chris Anderson says two factors are driving a new level of innovation. He says they are revelation and motivation. Here's how he defines them:
Revelation: for the first time, people can see what the very best people across the globe are capable of. A world of possibility opens up.
Motivation: if you can do something innovative and special, you get thousands of people viewing your work and talking about you. It's intoxicating. And it's driving hundreds and hundreds of hours of effort from potential innovators across the globe.
He makes a bold prediction: "it has the potential to transform any organization and give an amazing platform to any individual. I call it Crowd Accelerated Innovation, and I think it's about to ignite the biggest learning cycle in human history."
You can apply this principle to your writing or other creative projects. For the revelation phase, keep track of the most interesting and exciting things going on in your field (and other fields--often you can adapt ideas from totally different disciplines).
For motivation, figure out how you can get the most attention for anything innovative and special you do. Social media? An event? Collaboration with others who want to get the word out about their projects, too?
(For 100 case studies of people who came up with inexpensive but effective ways to market themselves or their products, get my book "Do Something Different," published by Virgin Books with a foreword by Sir Richard Branson.)