Add extra (all sortable) columns to the Users screen, showing:
- the number of comments, linked to the edit page for only that user's comments,
- the number of all custom post types authored, each linked to the matching edit page for that post type and that user,
- their registration date, and IP address used,
- their last login date, and IP address used,
- and their total number of logins.
Use the comment and CPT links to easily manage your users' output, and the registration and login data to track lazy spammers and trolls, or to see whether a new user is actually using the site.