The pagestats directive is supplied by the pagestats plugin.

This directive can generate stats about how pages link to each other. It can produce either a tag cloud, or a table counting the number of links to each page.

Here's how to use it to create a tag cloud:

[[!pagestats  pages="tags/*"]]

And here's how to create a table of all the pages on the wiki:

[[!pagestats  style="table"]]

The optional among parameter limits counting to pages that match a PageSpec. For instance, to display a cloud of tags used on blog entries, you could use:

[[!pagestats  pages="tags/*" among="blog/posts/*"]]

or to display a cloud of tags related to Linux, you could use:

[[!pagestats  pages="tags/* and not tags/linux" among="tagged(linux)"]]