How about the ablitity to send out texts to people the same way mass email is an option. More and more texting is used. Another tool to reach those that use Texting.
There's nothing wrong with otping out of these messages. Many people live/die by their cell phones these days and would be very interested in a simple text saying "camporee cancelled" or "last chance to sign up" or whatever it may be. There's also the option of donating via text and adding $5 to your phone bill to go to your organization.