datarumx

This WordPress plugin allows you to block access to static pages by one or more security questions. First, you have to create and add some questions with answers to the main list. Answers are case insensitive. Then, associate questions from list you created with pages you need to block. After question is associated with a page – page becomes blocked until user provides correct answers on questions associated with a page, if he does – access will be granted during current session.

Pageblocker "Seeya"

This plugin allows you to block access to static pages by one or more security questions.

spotlightstudios

This plugin allows you to search out and find posts with a specific password.
The plugin was developed with photographers in mind who may want to password protect their albums and give that password to clients, without having to provide dedicated links and or user-name login details each time.
This plugin will integrate with most custom post types and Gallery plugins including NexGenGallery and WP Photo Seller
<h3>Donations</h3>
Please Donate to: admin@spotlightstudios.co.uk or use the link below 
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=62YBJTBQ7HXLG

SS Find Post with Password

This plugin allows you to search out and find posts with a specific password.

Pageblocker "Seeya" vs SS Find Post with Password