Scirus
This search engine comes from Elsevier Science. As such, it covers
many disciplines, but searches can be restricted to "Economics,
Business and Management." It searches both scientific web sites as
well as various databases; the most interesting of the latter is
Elsevier's "ScienceDirect" (for their journals) and Academic Press
journals. Their "Advanced Search" has numerous useful options.
http://www.scirus.com/