With the availability of MEDLINE data to third-party developers, a host of alternative search engines have been developed recently. Some of the beneficial featuers of theses tools include: weighted tag clouds, bibliometric analysis tools, PDF full-text within search result, and natural language text processing of documents.
eTBLAST - Developed by the University of Texas Southwestern Computational Biology Group. Users enter entire portions of text and eTBLAST outputs a list of articles ranked by relevance to the original text.
GoPubMed - Developed by Transinsight and the Technical University of Dresden. Uses controlled vocabulary (MeSH) to sort results from PubMed queries into four categories: what, who, where, and when. Their statistics tool provides bibliometric analyses of the search results and allows you to see the most prolific authors, countries, journals and publication trends.
LigerCat - Developed by the Biology of Aging project at the Marine Biological Laboratory Woods Hole Ocenographic Institution Library. LigerCat maps MeSH terms from keyword searches and/or protein or DNA sequences to create a weighted tag cloud that quickly illustrates concepts from the initial query.
Novoseek - Developed by bioalama, a Madrid0based information technoclogy company. Keyword searches mine relevant documents from MEDLINE, PubMed Central, and US grants. Results are automatically filtered by key biomedical conceptys and bibliographics.
Pubget - Developed by a Boston-based team, Pubget immediately provides PDF full text in the search results.