Cool

The eTBlast Textual Similarity Search Engine allows you to find biomedical articles by putting in an entire paragraph. It will return abstracts from MEDLINE that match it closely. It is somewhat like PubMed's 'Related Articles', but is more targeted and you can combine those results to create a new query. From their own description:

* We sort our results by relevance, while PubMed sorts by date.
* We save you the time and effort of creating a complicated query.
* We let you iterate your search over several good papers to narrow your focus.
* We provide you the full MEDLINE abstract in our results, and a link to the PubMed page.
* We can send your results straight to your email so you never lose a reference or forget where you found it.
* This absolutely free service is provided by the University of Texas Southwestern Medical Center. No registration necessary!