http://zealdocs.org/ - 2 years old dev documentation browser. Maybe not exactly overlooked with 2400 GitHub stars, but never hit HN frontpage, and 0.1.1 was recently released. :D
I really love Zeal, but I wish the documentation files weren't being hosted from Dash's servers. If Zeal were available on OSX I'd use it in an instant.
Thanks! You can compile it for OSX yourself with some effort, but it's not going to be supported any time soon due to agreement with Dash's author, and is ugly being cross-platform as opposed to native like Dash.