In the past few months, a growing number of social networking, social change, and fundraising sites have made their debut.   These sites combine social networks and philanthropy and are designed to help nonprofits connect with potential supporters of their causes.  The most recent entry is Bring Light which launches today.  Co-founders Melissa Dyrdahl and Drew McManus left senior executive positions at Adobe Systems to apply their business, marketing and technology expertise to help donors and charities connect more effectively online.