Mendeley Desktop organizes your research paper collection and citations. It automatically extracts references from documents, generates bibliographies, and is freely available on Windows, Mac OS X and Linux.
Mendeley Web lets you access your research paper library from anywhere, share documents in closed groups, and collaborate on research projects online. It connects you to like-minded academics and puts the latest research trend statistics at your fingertips.
2. Copernic Summarizer
Copernic Summarizer is a tool to create summaries of scientific articles, reports, websites, etc. The tool uses language technologies that are as such good to look at!
Good tool to scan literature for research, although it cannot replace the actual reading after this scan. A free version can be downloaded (Windows, Linux under Wine).
3. Google Scholar
Google Scholar provides a simple way to broadly search for scholarly literature. From one place, you can search across many disciplines and sources: articles, theses, books, abstracts and court opinions, from academic publishers, professional societies, online repositories, universities and other web sites. Google Scholar helps you find relevant work across the world of scholarly research.