If you are doing research in the area of human rights, you might find HuriSearch a useful addition to your toolbox.
HuriSearch offers a fairly sophisticated front end, allowing you to query any of four types of source (NGOs, national human rights institutions, academic institutions, and intergovernmental organizations), search in any of sixteen languages, and use word variations if you wish. As well, search results can be filtered by facets: source type, source organization, country, and document format. Furthermore, you’re offered a permalink to your search and an RSS feed, so that you can stay up-to-date.
To my joy (and likely my fellow librarians) there is an advanced search option.
HuriSearch is a product of HURIDOCS, an international NGO helping human rights organisations use information technologies and documentation methods to maximize the impact of their advocacy work.