Catalogs

Washington Double Star Catalog
Maintained at the U.S. Naval Observatory, this is the main reference catalog that succeeds all others.
Alternative site

Centre de Donnèes astronomiques de Strasbourg
For all your data needs: EDS portal, Simbad object database, VizieR catalogue database, Aladin interactive image viewer.

Publications

Journal of Double Star Observations - JDSO
Autoritative magazine for double star observers, USA.

Il Bollettino delle Stelle Doppie - BolSD
Italian Double Star observers magazine.

Etoiles Doubles - Revue francophone des observateurs d'étoiles doubles
French Double Star observers magazine.

Webb's Double Star Section Circulars - DSSC
Directed by Bob Argyle, UK.

El Observador de Estrellas Dobles - OED
Spanish Double Star observers magazine, no more published.

Publications about "Stelle Doppie" web site

El Observador de Estrellas Dobles (OED) 12; 7 Gen 2014 (spanish)
Double Star Database, El cielo al alcance de un click
http://www.infoastro.com/dobles/oed12.pdf

Il Bollettino delle Stelle Doppie (BolSD) 2; July 2012 (italian, english)
Il sito web "Stelle Doppie"
http://ilbollettino.altervista.org/BolSD2/BolSD_2012_07_n02.pdf

Groups and users

IAU Commission G1 - Binary and Multiple Star Systems
Can also be found here

Toshimi Taki
Contains a free double stars atlas availabe in PDF format, and orbit calculation Excel file, a catalog file, and many other information about double stars.

Giuseppe Micello's (GMC) "duplicesistema" website
A very active italian double star observer.

Bruce MacEvoy's (MEV) Black Oak Observatory
The most comprehensive web site for double stars.

The Spirit of 33
An International Network of Double Star Observers, no more updated.

"Double Star Observing" forum on Cloudynighs.com

Gianluca Sordiglioni's (SDG) Stelle Doppie
This site.