Emergency Care and Transportation of the Sick and Injured (companion to text book, lots of little games)
Emergency Care (another companion to text, quizzes, good photo gallery)
Trauma scenarios. They're pretty advanced and much of the information is more relevant to hospital staff, but they're still good.
Interactive anatomy site
Tutorial and quizzes on heart anatomy, phys, EKGs and more.
Online training videos on a variety of good subjects
EMS Simulator - a classic. Really funny and light-hearted but follows true concepts.
ACLS simulators
Quizzes
Interactive tutorial, quiz on acid-base disturbances
Interactive tutorial, quiz on fluid balance
EKG Puzzler
Bioterrorism lessons and simulations
EMT-B quiz
Cardiac trivia challenge
Quiz