Datashades.info provides a publicly-accessible index of metadata and statistics on CKAN data portals across globe.
Data is gathered on portal users, datasets, resources, organisations, tags and plugins for each portal that can be accessed via the individual portal pages on the site.
As the index is refreshed, old data is kept in a historical index that can be explored on any portal page.
Datashades.info uses crowd-sourcing to build its index; if you know of a CKAN data portal not here, just search for it, and it'll be added to the site and global statistics.
So, please have a look around and do not hesitate to search for a portal not already present.