DjZoNe

This plugins main goal was to provide the ability to any of your registered users, to invite more people to the community.
Please notice, that this plugin totaly ignores whether the registration is enabled or disabled to your blog.
<a href="https://downloads.wordpress.org/plugin/invite-friends.0.3.zip" rel="nofollow ugc">Download now!</a>
<a href="http://invite-friends.dev.rain.hu/" rel="nofollow ugc">Support</a> | 
<a href="http://invite-friends.dev.rain.hu/faq/" rel="nofollow ugc">FAQ</a> | 
<a href="http://djz.hu" rel="nofollow ugc">Author</a> 
<a href="https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=djzone@cracker.hu&item_name=Invite%20Friends%20for%20Wordpress" rel="nofollow ugc">Donate</a>
Some functions:
<ul>
<li>invitation sending</li>
<li>invitation cards limit per site</li>
<li>after activation, the user is logged in automatically</li>
<li>after activation, the user can be redirected to a custom URL</li>
<li>activation screen is using the same styles as the login screen (if you have customized login screen it will affect the activation screen as well)</li>
<li>Dashboard for custom settings Plugins > Invite friends settings</li>
<li>i18n support (localized messages)</li>
</ul>

Invite Friends

This plugin give the ability to anyone how registered to your blog, to invite more people, even if the registration is closed.

minneapp

<a href="http://rss2email.me/welcome/bloggers" title="RSS to Email Welcomes Bloggers" rel="nofollow ugc">Rss to Email</a> links your blog’s RSS feed directly to the <a href="http://rss2email.me" title="rss2email.me" rel="nofollow ugc">rss2email.me</a> service so your readers can get daily email updates when you write new blog posts. This is very convienient to readers because the service is free to start and allows them to combine several of their favorite blog updates into one daily email.
You can read more

RSS to Email

The RSS to Email plugin allows visitors to easily subscribe (for free) via email to blog updates using the RSS2Email.me service

Invite Friends vs RSS to Email