An open source project I was working on was on the front page for about 2 days:

https://news.ycombinator.com/item?id=44292103

And heres the analytics from that time:

https://imgur.com/XGsiot4

I don't reallly bother tracking sign ups as its a totally free app, but from then to now, it looks like i've picked up about 1600 new accounts.