* There's an obviously good idea, people have tried it and "proved" that it cannot be done. Then somebody ignorant of this fact goes ahead and does it anyway. A famous example of this is Spencer Silver of 3M inventing the adhesive for the Post-It notes. He is quoted to say "If I had thought about it, I wouldn't have done the experiment. The literature was full of examples that said you can't do this."
* There's a good idea, others have implemented it with modest success. Then somebody comes along and blows it out of the water. Best example I can think of for this is the iPod. MP3 players were common before Apple, so it wasn't a new idea. Yet, they re-invented it in so many ways. Another example is, of course, Google, going against established search portals when they came about.
Personal experience - The author, Stephen Baxter, at a signing at the old Andromeda SF bookshop in Birmingham, UK, looked pretty sad because, despite being surrounded by fans, nobody actually wanted to approach him.
The legendary Kenny "R2D2" Baker at a convention I attended looked dreadfully alone; nobody even wanted to go up and ask for his autograph.
At the same convention there was a massive guy dressed like a Klingon warrior. He actually looked a little uncertain until I came up and regaled him with a couple of Klingon words. Then we got into some curse warfare and he was in his element. Yes, I speak Klingon as well.
I can cite many such examples, usually of some TV or movie celeb attending a convention and looking so bored, sitting there on his own. Dirk Benedict. Erik Menyuk. Michael Dorn. Many others.
* There's an obviously good idea, people have tried it and "proved" that it cannot be done. Then somebody ignorant of this fact goes ahead and does it anyway. A famous example of this is Spencer Silver of 3M inventing the adhesive for the Post-It notes. He is quoted to say "If I had thought about it, I wouldn't have done the experiment. The literature was full of examples that said you can't do this."
* There's a good idea, others have implemented it with modest success. Then somebody comes along and blows it out of the water. Best example I can think of for this is the iPod. MP3 players were common before Apple, so it wasn't a new idea. Yet, they re-invented it in so many ways. Another example is, of course, Google, going against established search portals when they came about.