Followistic

Hey, I'm Eric, the co-founder of Followistic. The basic functionality of Followistic (visitors can follow topics, categories and authors via email alerts) was a feature of a previous content aggregator of ours. The content aggregator didn't perform too well but the email alerts had amazing opening and click rates. In addition, some of the sites whose content we aggregated actually asked us if they could have this kind of email alerts feature as well. That's when we started to turn Followistic into a stand alone product. The idea is to show visitors the topics/categories/author of an article right below the article, give them the option to select what they are interested in, ask them for their email and that's it. Very simple from a visitor's point of view. For publishers and bloggers, Followistic is easy to set up and handles the entire process from showing the widget with the right tags to sending the email alerts and providing detailed analytics. I'm happy to answer any questions!

With Followistic you can enable your readers to subscribe to custom email alerts for all the topics, authors and categories of your website. The widget is fully customizable to your site’s look & feel and you can let your users set the frequency of notifications, select new topics to follow and unsubscribe from existing alerts, all from within their personalized dashboard. They also have a Wordpress plugin.

I really like this product!