How to use Lucid Dream / OBE abilites for useful purposes?

This issue is related to #58: Why practice OBE / do dream work?, but instead of dealing with motivational factors, it is about techniques and meditations to use to achieve specific, useful goals (like soul retrieving, getting information, etc.)

There is a lot of material that could fall within this category. We should start by creating a place holder so that information can be added as it appears.