If it is not something you are passionate about, there is no great website idea. Your passion for what you sell or believe in is what is going to draw buyers to you. In my six years in business I can tell you the only people who are truly successful are those who are selling their passion. I have personally coached several successful online business owners, some are now at the 5 million a year mark for income. In each case the owner is passionate about their product or service. Find your passion and build your website based on it.