Ok, this might be a little too confrontational for you to use with students (depending on your teaching style!) but I find it quite effective for myself. :)
Carrot2 is an Open Source Search Results Clustering Engine. It can automatically organise small collections of documents (search results) into thematic categories. With an instant overview of what's available, you will quickly find what you're looking for.
This is a brilliant site for students to use when their search needs to be more organised, educational, in-depth and/or focused.
Carrot2offers ready-to-use components for fetching search results from various sources including GoogleAPI, Bing API, eTools Meta Search, Lucene, SOLR, and more.
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