4 links
American Association of Variable Star Observers
aavso.org
The largest organization for variable stars: provides professional and amateur collaboration, research, and analysis of variable star observations.
Astronomical Society of South Australia
assa.org.au
ASSA's variable star group. News, FAQ, charts, and software.
General Catalog of Variable Stars Research Group
sai.msu.su
Research group working on the GCVS, Sternberg Astronomical Institute, Moscow, Russia. Includes catalogs and publications.
Information Bulletin on Variable Stars
konkoly.hu
The IBVS is a bulletin of Commissions 27 and 42 of the International Astronomical Union, published by Konkoly Observatory, Budapest, Hungary.