Great essay by Paul Graham at Y Combinator, the right way:
The way to get startup ideas is not to try to think of startup ideas. It's to look for problems, preferably problems you have yourself.The wrong way:
Imagine one of the characters on a TV show was starting a startup. The writers would have to invent something for it to do. But coming up with good startup ideas is hard. It's not something you can do for the asking. So (unless they got amazingly lucky) the writers would come up with an idea that sounded plausible, but was actually bad.
For example, a social network for pet owners. It doesn't sound obviously mistaken. Millions of people have pets. Often they care a lot about their pets and spend a lot of money on them. Surely many of these people would like a site where they could talk to other pet owners. Not all of them perhaps, but if just 2 or 3 percent were regular visitors, you could have millions of users. You could serve them targeted offers, and maybe charge for premium features.
The danger of an idea like this is that when you run it by your friends with pets, they don't say "I would never use this." They say "Yeah, maybe I could see using something like that."I think just about every product I've worked on at a non-startup has been the "wrong" way, where marketing / engineers come up with an idea and sell it to physicians, launch it, and hope it does well. In some cases, we may have worked the other way, but this was generally due to bad device design from the start and they wanted something fixed. The team rarely challenges where the project came from, because they generally come from executive management and it is a difficult position. Large companies aren't usually looking for breakthrough products (every one of them will say otherwise), they are looking for a solid return on investment.