I've found that by just sitting down and clearing my head and forcing myself to think really hard, trying to connect the dots half-baked ideas and just mixing it up with random thoughts, I've gotten a whole lot better at thinking up of ideas. Patrick (patio11)'s article about his not understanding why people complain they can't find ideas really gave me a good kick in the side and motivated me to do this: http://www.kalzumeus.com/2010/03/20/running-a-software-busin... and I do find his comment about "walking in a store to find what people buy" a great starting point! I also have this book which I recommend 'A Whack on the Side of the Head' http://amzn.to/bm6vW4 which certainly did literally help me look at ideas in a different light and generate new ideas.
As a part of my effort to just find new opportunities, I've been documenting meta-algorithms to find algorithms (if a business idea/model is an algorithm). An entry I just added is:
* Learn a new concept, algorithm, (e.g. 'Programming Collective Intelligence' http://amzn.to/cMLnKj), and apply it to some problem in a different field (e.g. non-technical things in real life, or things I use such as Facebook, Twitter, etc). <-- An example of this: I read up on Shazam's clever algorithm and tried to use that method to solve something else.
Does anyone else collect such meta algorithms?
Right now, maybe you're reasonably content with things in your life. You've explored your problem space and solved anything causing stupid problems. Add a hobby, and you increase your problem space, and you may find new itches, that you didn't have before, that need scratching (to mix metaphors).