I have been searching for a plugin like this for months. There are few things I wanted to do. Firstly a secured site using the WordPress user authentication (allegedly very safe) for registered users only. Then a static first page using a plugin like this one by Semiologic. Lastly it would be nice to incorporate the default WP login screen into the blog. A static first page will display identify of the site for organisation like school, church and closed community etc.
I used a few times the script by ioerror as described in my early post here. Then I found this Anth Only plugin by Owen Winkler.
At this experimental site I now have a static first page, login is available there instead of the boring WordPress page and the blog isn't viewable until you are logged in. Great plugin that serves 3 needs.
This first page is in fact a login.php file in the theme folder. This file is called instead of the normal index.php file when the plugin is activated and you have that file created. I have also called few functions from plugins showing site statistics and handy links which I expect users to use without logging in.