Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Bloomerang - Bloomerang is a simple donor database and fundraising software solution that helps nonprofits decrease donor attrition and increase revenue.
Membee - Membee is web-based membership management software.
Kindful - Nonprofit donor database + fundraising tools all in one
Galette - Galette is a membership management web application towards non profit organizations.
Classy - Expressive, flexible, and powerful stylesheets for native iOS apps