Here are some excellent audio guides to mindfulness.
There are four exercises here which are related to Acceptance Therapy
http://act-for-anxiety-disorders.com/therapist_materials_audio_files.html
There are some good 2-3 minute clips from Jon Kabatt-Zinn here:
http://www.nightingale.com/pa~product~Mindfulness_Meditation~audio~1447.asp
There are some good introductory talks on Insight Meditation here:
http://www.buddhanet.net/audio-meditation.htm
