Restrict access to readers who login with a permitted email addresses (no usernames or passwords!). Ideal for private/personal/family blogs.
Want to restrict access to your blog to friends and family only, but don't want the hassle of everyone remembering (and forgetting!) usernames and passwords? Friends Only requires users to "log in" with their email address before seeing anything in your blog. It's not particularly secure, but it's a great way to make sure that random people don't have easy access to your blog.
This plugin also blocks access to RSS and Atom feeds. If you want to re-enable the feeds on your blog, you'll have to use the Feed Wrangler WordPress plugin to create unique URIs for your feed (this plugin is set up to allow Feed Wrangler feeds through). See FAQ for details.
Also, make sure that each email address is on its own line, and without any decoration (firstname.lastname@example.org is okay, but "Some One" [email@example.com] is not).
You can also use your own custom CSS. See FAQ for details.