List number of posts per user. You can limit the search by date, post type and user name.
Get an overview over how active your users has been during a specified time period. This plugin will list all the users, the number of posts/pages they have created and when their latest post was created.
You can sort all the columns, filter by post type and search for a specific user name.
Note: This plugin uses the WP_List_Table, even though it is marked as @access private in WordPress core.