Offer HN: do you want anything built?

I am a web developer with some free time on his hands and out of ideas. Recently, I've been wondering if I could improve the world by making something for the community I value.

My question: is there a web application / service you would desperately like to see built? What is it?

I don't give promises or guarantees, I am not even sure whether my whole idea is good, but it's better try and fail than not try, right?