Wright's Anesthesia & Critical Care Resources on the internet has a database of links and internet resource materials relevant to critical care.

Critical Care Forum an online forum for critical care, intensive care and emergency medicine. 

CCM-L an international critical care internet discussion group.

Pediatric Critical Care

PedsCCM a multidisciplinary, educational and practical resource for pediatric critical care medicine.

picuBook an online textbook of pediatric critical care. 

Virtual PICU an online network of pediatric critical care units creating a common patient database.

Neonatal Critical Care

Neonatology on the Web dedicated to the promotion and linking of WWW sites concerned with the medical care of premature and sick newborns.

Critical Care Organizations

Society of Critical Care Medicine including a resource page with links to information and websites relevant to the practice of critical care medicine.

Critical Care Assembly Site of the American Thoracic Society.

American College of Chest Physicians with online Pulmonary and Critical Care Update.