Messaging and Notifications
Do you have a member base or want to grow a membership website? Keeping people informed is tricky because you don't want to overdo it. Step over the line and it's "unsubscribe" time. How can we keep people in the loop without getting on their nerves?
The overall strategy here is to give them choices -- and some control -- because people like their information in different ways. I am subscribed to various sources in many sorts of ways. I'm on email lists and I follow certain twitter feeds. Others are suitable for Facebook follows and RSS feeds.
I love to create alerts. I have an assortment of daily and weekly alerts on Google news. We can offer this kind of control on your Drupal site too. Site users can sign up (and easily adjust or unsubscribe) to content feeds that they can tweak and filter themselves. A user can sign up for topics (taxonomy terms) or content types (news, blog posts, events, etc.) or a combination… and also select the frequency. They can be instant or weekly or somewhere in between.
For example, let's say you have a discussion forum on your website. You can "subscribe" to a thread you commented on or perhaps to every thread if it's not too busy of a forum. You probably need this if you are the moderator! But instead of getting a whole bunch of messages, you can opt for a daily or weekly digest that catches all of the posts.
Notifications don't necessarily have go via email. They can just show up inside the webpage (while user is logged in) or be sent out in other ways such as Twitter, Facebook, and Feeds. You can even set up SMS text messages but this runs more expensive.
And along these same lines, users (members) of your site can message each other directly through the website without having to reveal their email addresses or other contact info. Funneling contact messages securely while keeping contact info private is a core feature of Drupal.