Limit Sign-Ups per IP Address
Allows only a few new accounts per IP address per day, which stops bots and people from creating piles of accounts.
Snippet Library
Users snippets for WordPress
Snippets for user accounts, roles and profiles: extra profile fields, new columns in the users list, last-login tracking and tighter control of what each role can do. Handy for membership sites, client sites and teams with many authors.