I think you're overgeneralizing, especially 100 various things can be understood under the term "meditation". There is a program for mindfulness-based stress reduction using meditation as one of the elements, with scientifically proven effects: http://www.mindfullivingprograms.com/whatMBSR.php

Addressing the original question, this is an exceptional introduction: http://www.amazon.com/Miracle-Mindfulness-Thich-Nhat-Hanh/dp...