Electronic, and by sources I mean forums or blogs. Somewhere with interesting people like HN, but with an electronics focus.
It was 4 or 5 years ago that I first heard of Stripe Snoop http://stripesnoop.sourceforge.net/ I thought it sounded like an interesting project, I'm not sure if it's dead now, but certainly interested me at the time. I was also intrigued by Zed's rant about programmable peddles.
The best one I know is the Sparkfun forum. It's heavily weighted towards newbies, so it's not as interesting as HN, but it seems to be growing fast. There are quite a few fun projects being discussed there at any given time.
It's interesting how software people congregate. It is really hard to find a good electronics blog or forum that isn't populated primarily by professionals talking about work-related topics. Electronic or Mechanical engineering versions of HN just don't seem to exist, unfortunately.
[edit] I know there are hobbyist electronics and machinist blogs out there; I'm saying that people with electronics & mechanical skills aren't discussing their startup ideas online.
Maybe one of you can share alternate sources for hardware.