Based on the Pending Submission Notification plugin by Razvan Horeanga

This plugin helps you to keep an audit trail of user login activities such as successful login, logout, failed login and more to ensure your site performance and monitor potential hacker attacks.

Keep your WordPress site up-to-date and disable email notifications about WordPress updates.

This plugin is designed to send an email notification whenever a draft is saved.

Sends an email to a pointed email address when an admin user logs in

Get email notifications when Facebook Comments are posted on your WordPress website.

Happy Birthdays reminder keeps in remembrance wp users birthdays via email reminders and a page display via shortcode.

WPLogger is a real-time user activity and monitoring log plugin. It helps WordPress webmasters keep an eye on what is happening on their websites.

Livefyre Comments 3 replaces your default comments with real-time conversations. Our social integration features make it easy to capture all the conversations going on around your content across Twitter and Facebook, while pulling your friends into the conversation.

The easy and ultimate solution for notifiaction that lets your customer set notification for product availablity and/or discount.

Email notifications for pending review content submission.

The Post Status Notifications plugin by 99 Robots provides an easy way to notify Administrators when Contributors submit posts for review or when a Contributor post is published.

Plugin sends notifications by email after successful and failed login actions with detailed information about the user and his location.

Add annotations to any part of a blog post. Livefyre Sidenotes allows bloggers and readers to annotate content in a simple, mobile-friendly interface you can moderate.

Simple post status notifications sends emails to authors and editors when the post status changes.

Subscribe to Comments Reloaded allows commenters to sign up for e-mail notifications of subsequent replies. Don't miss any comment.

User support plugin. Registered users will be able to create/ reply support tickets. Admin can reply on the tickets from admin panel.

Enable your customer to add out-of-stock products into their waitlist and get notified when the product becomes in-stock and can place the order easily.