Aiddata .org provides over 1 million data points of information on aid flows from a large range of donors, creating an unprecedented level of transparency about international aid. The information covers most official aid bodies (e.g. DFID, USAID, et al) and the latest version (3.0) also includes data on private charity organizations in the US and flow of remittances. The data can be downloaded in full or visualized online. There is also a robust API system to build apps on top of the rich database.
Based on a quick review of the datasets, I feel that it would be a great source of information for researchers and planners who would like broad level information. I tried to explore the data wearing the hat of a citizen interested in monitoring funded projects, and found the dataset wanting from that perspective. The location of the projects is not clear and description of projects included were too broad to be of much use for monitoring from the grassroots. Perhaps a deeper exploration of the dataset may make me change my mind.
One potentially useful feature that they have created is to enable people to provide additional documents and to respond to information provided on various projects. With some mobilization, such features can become highly useful for gathering feedback from the grassroots on various projects.
Despite the likely limitation that this is not a project meant for the grassroots, aid data provides a great platform for research and for building interesting applications. It would be interesting to see its uptake beyond the academic community.