Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.

Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.

Tax990 - Tax 990 is an IRS-authorized e-filing solution for nonprofit organizations that helps clients understand the process of filing 990 series returns.

Diigo - Diigo is a powerful research tool and a knowledge-sharing community

Qiqqa - Qiqqa is a free research and reference management software. It can be used in many organizational projects from the academic to the personal to the business endeavor. Read more about Qiqqa.

Weava - Workspace to highlight, organize & collaborate on your research articles.