If you are new to mindfulness and meditation (and even if you are not!) Rehena has kindly put together a list of recommended books, websites and courses/retreats here.
There are many other wonderful resources that you may find useful:
Talks by Thich Nhat Hanh and monastic Dharma Teachers
Talks by Insight Meditation tradition Dharma Teachers
Details and links to podcasts of talks by Gaia House and other teachers are available from http://www.dharmaseed.org/talks/ There is an RSS feed you can sign up to for individual teachers.
Talks by Ajahn Brahm and his monastics
Buddhist Society of Western Australia
Talks by various teachers at London Insight Meditation