• eMARS - Major Accident ReportingSystem (This database is maintained by the Major Accident Hazards Bureau (MAHB) and is  related to the EU Seveso II directive on major accidents involving highly hazardous substances)
• FACTS - Failure and Accident Technical Information System (This database is operated by Unified Industrial & Harbour Fire Department in Rotterdam-Rozenburg)
• ARIA - Analyse, Recherche et Informations sur les Accidents (is operated by by BARPI, a part of Ministère de l'Aménagement du Territoire et de l'Environnement  MATE)
• PSID - Process Safety Incident Database (is operated by the Center for Chemical Process Safety CCPS)
• NEDIES - Natural and EnvironmentalDisaster Information Exchange System (is operated by the  Joint Research Centre, Natural Risk Sector) 
• ECCAIRS - European Co-ordination Centre for Aviation Incident Reporting Systems
• Aviation accident database & synopses (is operated by the  NationalTransportation Safety Board, USA)
• IRTAD - International Road Trafficand Accident Database (OECD)
• WOAD - World Offshore Accident Database (is operated by Det Norske Veritas DNV)
• Accident statistics for fixed offshore unit son the UK Continental Shelf (UK HSE report)
• Accident statistics for mobile offshore units on the UK Continental Shelf (UK HSE report)
• Ship/Platform Collision Incident Database (UK HSE report)
• AirSafe.com
• PlaneCrashInfo
• Danger Ahead - Historic Railway Disasters
• BBC Disaster News

Note that links have been removed, but they should be easy to retrieve by a search.