A lot of people know this already, so it may be a repost considering how long it's been around, but for those of you that don't know:
If you are dead in instance and are grouped, so long as you aren't the party leader, you can disband instead of releasing and once the 1 minute 'you are not supposed to be in this instance' is up, you will be ported back to wherever your hearthstone is set to and will be alive, without having to get your corpse or having to pay the spirit healer's 25%.