Shimon Rura, the creator of Frassle, shares some great lessons about building web applications:

Yet overall, the core problem with frassle is that it tries to do too many things. It makes conceptual sense to integrate blog publishing, aggregators, republishing, and semantic correlation. But it doesn't make practical sense. In trying to tackle all of these issues at once, I was never able to be the best at any of them. That weakness almost completely prevented users who tried frassle from ever coming back, because when a user is trying a web app, they're not looking for long-term conceptual potential. They're looking for tools that solve a specific problem or make life noticeably better in a matter of minutes. If an app doesn't walk a user through a pleasant experience in the first 5 minutes, that user will not come back. And if you can complete the experience in less than 5 minutes, you will roughly double user retention for each minute saved. I didn't fully appreciate this adage until voo2do, which took a lot less novel thinking and implementation time than frassle, got more users in a week than frassle had in two years.