We were going to build something like this to integrate to our web based data management system. Non profits can send out invites and then anyone that responds "yes" (or whatever) would automatically be put into the non profits database of contacts.
www.HawaiianHope.org - Providing technology services to non profit organizations, low income families, homeless shelters, clean and sober houses and prisoner reentry programs. Since 2015, We have refurbished over 11,000 Computers !