Conference Service: mathematics, physics, nuclear applications, chemistry, earth sciences, computer science
Chemistry Conferences: chemistry, biotechnology, nanotechnology, life sciences, chemoinformatics, engineering
Microbiology conferences: Straightforward list of worldwide microbiology conferences, meetings, symposia, and more
Molecular biology conferences: Another straightforward listing of orldwide molecular biology conferences, meetings, symposia, and more.
ResearchGate Events: Scientific conferences, workshops and other events, primarily in the life sciences
Computer Science Conference Search: confsearch.org (computer science conference calendar and search engine)
Call for Papers Wiki: alphabetical listing of calls for papers in academia
InterDok: locate future conferences, congresses, meetings and symposia
All Conferences: Global conference directory for conferences, conventions, trade shots and more.
Conference Alerts: Academic conferences worldwide (emphasis on international)
Research Bib: Busy website but many leads
International Academic Conference System: Seems to be a copy of Research Bib, but many leads
H-Net Announcements: search and browse for academic conferences, calls for papers, and programs in the humanities and social sciences