I've been working on a web app for listening to and sharing podcasts called Flapcast. I built the site for myself so I can listen to my podcasts on whichever computer I'm on (and share my favorite episodes with my friends), but It would be great for it to get enough traction that the social element will take off (making it better to discuss and discover episodes with new people).
Its been online for a few months now, with almost no traffic, and then I inexplicably got picked up by Lifehacker last weekend (I think they found me on makeuseof.com, which posts stories on all sorts of web apps, so I'd definitely recommend other developers to submit to sites like this). It was incredible to get my idea validated like this, but I'd love to hear feedback from the HN community on the site (since there seem to be a lot of podcast lovers on here too).
http://flapcast.com