Common Usage Database (cudb)
A couple of months ago I was searching for an excuse to write an application on Google App Engine. After mucking around with the Datastore and authentication API I decided to rewrite Most Common Usage on Google App Engine.
The end result was the Common Usage Database and like Most Common Usage the website is focused on the usage of CLI commands in Linux and Unix-like operating systems.
The website uses Google for authentication so you don't need to signup if you
already have a Google account. I've also setup a Google Group and the
#cudb channel on Freenode.
I look forward to creating a repository of useful commands and providing an easy and open way for developers to use that repository.
Link: http://www.cudb.org/