When you have a Chaptercore site, there are many ways that your users can interact. It does wonders for internal communication.
How many times have you been frustrated with the amount of "spam" entering your inbox from your other members? Take discussions like that to your website, where they have a place. With a private message forum, you have the choice of whether you want to see those messages or not.
Private message forums are also a great way to keep in touch. After members graduate, it's a good central location to coordinate meetups and see what people are up to.
Any member of your website can create their own private photo galleries that only logged-in users can see. This is a great way for alumni to share what they're up to with the other members of your chapter.