We've all got that great idea for a website in us, right? Well, if you think it's great, run with it before someone else does.
If you're looking for ideas, don't think a site first, think about a service. If it's a product, think about how you might serve the customers better than others.
Do your research, take your time to look what's out there, and then talk about it with people that might use that service. You can have them sign NDAs if you think they may steal your idea.
The Net gives us every opportunity to locate new services, and you should spend time looking at potential competitors, as well as similar services in a different niche. I recently found a niche service targeting a small sector of consumers, and, without too much trouble, thought about how the service could be adapted to another niche, or even rolled out to a whole range of niche sectors. Don't just stop at a web based service, think about how it would work as an app, or even a product with the technology built in.
Once you're satisfied you've got an idea, get yourself a business plan to establish the costs, the resources, the ROI, the funding, and if you need it, investors. Also, longer term, look at how you might sell the business on to others so you can reap the rewards.
Whatever you do, do your research and understand the market and the potential demands.