Logical Captcha takes advantage of the TextCaptcha.com service, which provides logic-based textual questions instead of distorted images or audio to validate that the entity registering is a real live human being, and not a spam bot. It will provide protection against false registrations and the dreaded spam comments, etc.
An example of such a question might be:
Question: 
Out of a truck, a lion, the color purple, and the number forty-two, which has a door?
Answer: 
truck
Textual logic-based captchas mean that your registration process will be accessible to everyone, including visually/hearing impaired visitors who use access technology to surf the web. It requires a free API key from <a href="http://TextCaptcha.com" rel="nofollow ugc">TextCaptcha.com</a>
This plugin was developed by Josh de Lioncourt of <a href="http://maccessibility.net" rel="nofollow ugc">the Mac-cessibility Network</a>, a site dedicated to blind and visually impaired users of the Mac OS X operating system, the iPhone OS, and other Apple Inc. products and services. Josh de Lioncourt, the Mac-cessibility Network, and related sites are not in anyway affiliated with TextCaptcha.com

Logical Captcha

Integrates a logic captcha to verify that the registrant is a human and not a spam bot instead of using distorted images or audio.

Jonathan Lau

CubeAccount Frontend Login lets your users login and register from the frontend of your site.
The WordPress dashboard and admin bar can be hidden completely from your users. 
Users trying to reach wp-login.php directly would be redirected to your custom login page.
Installation is as easy as activating the plugin.
If permalinks are enabled, login and registration URLs would be rewritten to /login and /registration automatically.
Works well with other plugins that adds features to the login and registration form.

CubeAccount Frontend Login

CubeAccount Frontend Login lets your users login and register from the frontend of your site. The WordPress dashboard and admin bar can be hidden comp …

Logical Captcha vs CubeAccount Frontend Login