One thing that most forum software is missing is a decent mobile view.
More and more people are viewing their favorite websites using a mobile device.
Tapatalk is one solution but it is a dedicated app that has to be bought.
For ezForum I would like to have dedicated css as option for different mobile devices. Which will allow creating custom views for devices such as the iPhone, iPad etc
SMS -
For topic replies, watching certain topics, login attempt notice, secondary password recovery.
SMS can also be handy for event notification as well.
I do have experience with SMS what would probably happen is some kind of API intergartion to a third party to send the sms.