UNHCR - UN High Commission for Refugees
OHCHR- UN Office of the High Commissioner for Human Rights
Shadow reports are a method for NGOs to supplement and/or present alternative information to reports governments are required to submit under treaties. NGOs play an essential role in providing reliable and independent information, which may be overlooked in a government's report. NGOs around the world use shadow reports to lobby various United Nations' bodies, including treaty-monitoring bodies, thematic groups, charter-based bodies, and the High Commissioner for Human Rights.
Some examples are below. There does not seem to be a comprehensive site with all submitted shadow reports, so search for them by Googling combinations of the NGO that might submit a report, the country the report is about, the right that the report discusses and the phrase "shadow report."
Think tanks are institutions that generate public policy research, analysis and activity. Their output can include publications, reports, blogposts and journals. They can be independent or affiliated with other organizations. Most are non-profit, but some are funded by governments, advocacy groups, or corporations, and may derive revenue from consulting or research work related to their projects. They can be non-partisan or partisan, so pay attention to the goals of the organization when using the information they generate. You may also want to read the Wiki entry for each think tank to get an outsider's perspective on their goals. When available, I have used included WIki info in the descriptions below.
Harvard's Kennedy School Library has a website with some useful information on how to evaluate think tanks and their research. They have also created a custom Google Search of over 600 think tanks:
Some related think tanks you may want to investigate include: