I assume you are almost doing something for living. May be you can come to great ideas and pain points in your OWN business. Most of the great startups started by founders scratching their own itch. You should be more alert while living you daily life.

There is also another method suggested by Pual Graham think about your daily task and imagine them 100 years later. How do you think they will be perfumed in the future?

Also here is a recommended read for you if you hadn't read it before David http://www.paulgraham.com/startupideas.html