This is not a joke. I realize that hn is not a web app in the classic sense, but I get far more value from hn than any webapp. Let me explain...
I learned long ago that increasing productivity was like "striking out the pitcher". You got small, easily measured, and much appreciated improvements. But the real improvements come in major shifts in thinking and processing.
I once had a choice of 2 projects to work on, each about the same amount of work for me. One would save 8 people 10 minutes per day. The other would change an entire business process, potentially saving millions of dollars. Believe it or not, I chose the first because I didn't understand the ramifications. Until my first mentor stopped me and pointed all this out (That's how he became my mentor.)
I have looked at several web apps and desktop tools but eventually rejected them all (except for Textpad which rocks). I'm just not interested in saving a few minutes here and there. (I also realize that there may be many web apps that go beyond simple productivity improvements.)
Hacker news, OTOH, changes the way I think all the time. Once or twice a month, I come across something that improves my work by magnitudes, not percentages.
I also get my creative juices flowing simply by participating. It's hard to place a value on that.