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
    * HAML
    * LowPro
    * Prototype
    * Nginx
    * Ruby
    * Vlad
    * Git

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

best regards,