Article Sciences - - Scientific article search and order engine, a service provided by Institut de l'Information Scientifique et Technique (INIST) of Centre National de la Recherche Scientifique (CNRS), France.
CiteSeer - - Search engine for computer science and related matters. For all results number of citations are given which allows to estimate the importance of a paper in a given context. Most of the papers are cached and available for direct download as postscript or PDF.
ISI Highly Cited - - A search tool to identify individuals, departments and laboratories that have made fundamental contributions to the advancement of science and technology in recent decades.
iSpecies - - A species search engine from Rod Page of Glasgow University. Search on either the common or Latin name of a species. Results are generated by querying other data sources.