Paste a paragraph from an article, paper, etc into this search engine and get back a list of relevant or similar articles. On first inspection, it seems pretty fantastic as a search engine, but has very very limited results. Very very few sources.

The Learner's Library™ is a simple and intuitive search tool that locates relevant material from any text based content repository...our Virtual Research Assistant allows you to input whole articles, papers, notes or outlines (up to 10000 words at a time) and get back the materials you need for meaningful research....our custom publishing interface allows the easy creation of custom coursepacks and reading packs with but a few clicks.... our CiteRight® citation checking tool examines your written work and shows you what in your work needs a citation from material in the content repository.