by Sergey Biryukov on WordPress.org
Allows users to register with Cyrillic usernames.
Allows to create users with usernames containing Cyrillic characters.
Integrates a logic captcha to verify that the registrant is a human and not a spam bot instead of using distorted images or audio.
A must use plugin for any WordPress site with necessary features.
Hidden Comment Field provides functionality to block more spam by adding hidden field with jquery