When I land at web apps or sites upvoted here in HN, most of the time I wonder - how these sites were developed. Figuring out all architectural, technical and UI aspects of an app or a site would be inspiring to a developer-cum-lurker like me.
Shall we start with http://github.com
A few I found interesting:
* https://github.com/blog/517-unicorn
* https://github.com/blog/542-introducing-resque
You also might want to check out their public projects: http://github.com/github
Or those of the founders:
* https://github.com/mojombo
* https://github.com/defunkt
* https://github.com/pjhyett