This WordPress plugin (tested on 1.5.x & 2.0) will make your blog accessible only to logged in users.
A must-have for paid-content publishers and privacy concerned bloggers.
This is a simple zero configuration plugin. It allows you to view any content, if and only if you are logged in.
Paid Content Publishers
If you want to use WordPress to display paid-content to your users then this plugin is for you. It allows you to display your articles only to registered users. You can prevent non-paying users from registering on your blog by unchecking Anyone can register checkbox in Options / General screen. And then you can manually register the paying members (Users / Authors & Users screen under Add New Users section) who will then have access to site contents.
If you want to make your blog accessible to few people only (like family and/or friends) then this plugin is for you.
If you are writing on senstive topics which may cause problem in your professional / personal life then you can use this plugin to restrict access to the contents of this blog. Only you and your selected users will have access to the contents.
This plugin makes the whole blog inacccessible for non-logged in users including search engines. So long this plugin is active your blog contents will be inaccessible to search engines.
Read more and download: Angsuman’s Authenticated WordPress Plugin - Password Protection for Your WordPress Blog