The following approved validators and verifiers are:

UNFCCC Clean Development Mechanism
Designated Operational Entities approved under the Clean Development Mechanism
The list of DOEs is at: http://cdm.unfccc.int/DOE/list/index.html

UNFCCC Joint Implementation
Accredited Independent Entities (AIEs) approved under Joint Implementation. The list of AIEs is at: http://ji.unfccc.int/AIEs/List.html

The VCS Program is currently considering approval of Certification Bodies (CBs) approved under the Californian Climate Action Registry. The list of CBs is at: http://www.climateregistry.org/SERVICEPROVIDERS/Certifiers/