Paul Buchheit at Startup School '08: Focus on making 100 people happy, and then you'll be validated for opening up your app to more people. I don't think it's

Paul Buchheit at Startup School '08: Focus on making 100 people happy, and then you'll be validated for opening up your app to more people. I don't think it's that difficult getting 100 people (especially if you offer private beta invites to smaller niche sites that you're targeting). Plus it gives you a chance to understand what your customers want, which is crucial to early development in an application. You'll need to constantly get customer feedback and validation.