I have no problem dreaming up ideas for businesses. It's a temptation I have to deliberately resist, actually, because I think it interferes with the more important activity of finding opportunities for businesses, which involves searching the world around you, not just the combinatorial creativity of your own mind. So for me, the best thing to do is to move in circles where you meet other people who are also interested in starting new businesses or expanding current ones, and discussing problems and opportunities with them. The chances are good that alone, none of you have a great idea, but together with some chemistry, networking and collaborative complaining, an idea might emerge that actually does not suck, and as you beat it up more it still does not suck. My experience is that most everyone is really smart about something, so try to find people who are really much smarter than you in some area, and bring your own unique smarts to that, and groan and moan a lot.
Why do I mention groaning and moaning? I think it is because in my own experience, the initial idea that brings a group together is rarely the one that gets launched. Instead, it is the whipping-boy. It is interesting, but it draws attention from smart people who say that this isn't the way it should be done, that is the better way, and someone else modifies that more, and someone says, that'll never work until you do this, and so the non-sucky idea slowly finds its expression.
The lone genius with the sudden flash of insight is actually, in my experience, not the one who produces the actual thing people do - they produce the soccer ball people kick around as they gel into a team. The team produces the really good idea.