'Grey literature' is a phrase used to describe research that is published in non-conventional places and are not indexed by the major databases. Examples could be conference papers or government reports.
Use the following sources to track down grey literature.
OpenGrey
System for Information on Grey Literature in Europe. The website covers unpublished European literature on Science, Technology, Biomedical Science, Economics, Social Science and Humanities.
The Grey Literature Report
An online publication covering (mostly) American grey literature
ELDIS - International Development
ELDIS is an online information service providing free access to relevant, up-to-date and diverse research on international development issues.
GreyNet International
This search engine provides links to grey literature sources.
BASE
Bielefeld Academic Search Engine
ADS - Grey Literature Library
Unpublished fieldwork reports and grey literature from the Archaeology Data Service
