Thanks for sharing. We've had a couple of additional web app ideas, and I think figuring out your user funnel is the most important part of deciding to move forward.<p>After a bit of discussion, we've decided to identify a few key pain areas and then brainstorm apps around those pain areas rather than taking the first idea that comes to mind. With the app market the way it is, a good idea isn't good enough. You need something that fits a market (that's preferably under-served or mis-served), has a good viral component and is novel. Engineering what app to approach is almost as hard, and less straight forward, as developing the app itself.
Your first point hit home way too quickly! I made similar mistakes in my first 'business' which really made me appreciate the difficulties in starting a community oriented website. I found that I didn't truthfully answer the question about what value it provided and whether there was truly demand or whether it was a build it and they will come approach. When I left Co-opRatings the adage every end is a new beginning really came true though, good luck on the new endeavor!