CiviCRM is a free, libre and open source software constituent relationship management solution. CiviCRM is web-based, internationalized, and designed specifically to meet the needs of advocacy, non-profit and non-governmental groups.  CiviCRM allows organizations to communally manage contacts, segment mailing lists, events, reports, fundraising contacts and more.

Uses

CiviCRM can be particularly useful in large-scale election monitoring projects engaging multiple groups and/or requiring coordination between multiple partner organizations.  It can help organize critical contacts and information to reduce overlapping efforts and promote effective communication with supporters.

Useful Links

CiviCRM website
CiviCRM blog
CiviCRM demo
CiviCRM on wikipedia