BuddyPress: Limit the Length of Activity Updates
Shortens activity updates and comments longer than a set number of characters, which keeps the stream readable and discourages wall-of-text spam.
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.
BuddyPress: Only Friends Can Send Private Messages
Limits BuddyPress private messages so members can only message people who have accepted their friend request, which cuts down unwanted messages.
Limit How Many Users a Role Can Have
Caps the number of accounts for chosen roles, such as a maximum of 3 Editors, and blocks adding or promoting anyone beyond that limit.
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.
Only Allow Registration From Certain Email Domains
Limits sign-ups to email addresses at the domains you list, for example your company or school domain.
Require an Invite Code to Register
Adds an "Invite code" field to the registration form and only lets people sign up with one of your codes, each with an optional limit on how many times it can be used.
bbPress: Limit Certain Forums to Specific Roles
Lets only chosen roles open particular forums and their topics, for example a "Staff" forum for editors or a "VIP" forum for paying members.
bbPress: Limit New Topics per Member per Day
Caps how many new topics a member can start in 24 hours, which stops spammers and over-eager posters from flooding the forums.