Ask HN: Got any simple website ideas?

Does HN have any ideas for a simple website? I am currently busy evaluating several web frameworks for my future projects. I am looking for some simple, small website ideas that I could implement in order to evaluate these frameworks. Just building "Hello, World!" applications or the same basic blog over-and-over again doesn't really appeal to me. I'd much prefer to build something actually useful while I'm at it :-) I have read that some of you have ideas all the time. I'm stumped, so I'd gladly take any of your ideas that you are not going to implement anyway!