WEBDA
A site devoted to open star clusters. It is mainly intended for professional and amateur astronomers
http://obswww.unige.ch/webda/

Catalogue of Open Cluster Data (5th Ed.)
A computer readable catalogue of open cluster data compiled by Gosta Lynga, Lund Observatory
http://cdsweb.u-strasbg.fr/cgi-bin/Cat?VII/92A

Catalog of Bright Open Clusters
from ARVAL observatory.
http://www.oarval.org/OClust.htm