Web app for implementation footprint of web apps (!)

I was wondering (http://inormalized.com/2008/8/13/web-app-
implementation-footprint) if there is any sort of web app out there
which holds information about tools used on other web apps.

Like eg nubyonrails.com has

Manufactured with

* Merb
* LowPro
* Prototype
* Nginx
* Ruby
* Vlad
* Git

is there something like that out there that (google doesnt know
about;) )?

best regards,