Limit rate of login attempts and block ip temporarily (Up to 10 minutes). It is protecting from brute force attack.
The plugin Limit Attempts allows you to limit rate of login attempts by the ip, and create whitelist and blacklist.
The most advanced protection against sploggers and spam users registration, is fully WordPress,WordPress MU ,BuddyPress and bbPress 2.0 compatible
To block users from admin side except admin users for specific day,time, and date or permanently.
Spam Master is the Ultimate Spam Protection plugin that blocks new user registrations and post comments with Real Time anti-spam lists.
Allow members of the forum to selectively have a user's posts and topics hidden from view.