There are many social networks on the Internet. Try Meetup.com to find interest groups that meet in your geographic area. For example – you click on the tab for “Meetups by City” and you browse categories and topics that are interesting to you. In the listing it will show the number of people in any group. You can click on a group and find out their profile and activities and if you are interested you can signup for the group. There is no charge for joining groups. Some groups do ask that you send in your information before you will be joined as a member.
Then you can RSVP for specific group activities. This is a great way to meet people who share your same interests. These include professional interests such as business networking, social such as hiking or cooking, sports etc.
For your nonprofit promotion you can look for groups that might be interested in your organization. You can also setup your own meetup group.