Network for Good's Online Giving Index
Network for Good, the tool that powers donations to the charities rated by Charity Navigator, has a unique perspective on the experience and behaviors of charitable giving across several distinct channels including: individual charity websites, charity portals and social giving (peer-to-peer) websites. They released a report, The Online giving Study, in 2013 that examined $987 million in online giving through Network for Good’s service (giving that took place on sites that do not use the Network for Good or that were made offline are not included), to over 100,000 different nonprofits from 2001-2013.
M+R Benchmark Study
The M+R 2014 Benchmark Study provides data regading online fundraising and advocacy.
The Blackbaud Index of Online Giving
Blackbaud's index covers the online giving trends of over 3,300 nonprofit organizations representing $1.7 billion in yearly online giving. The Index is based on actual revenue statistics from nonprofit organizations of all sizes and a variety of missions.
More reports, such as how online varries by the size of the charity and by the mission of the charity, can be found on the Blackbaud site here.