As a backwards Zen practitioner, these meditation tools seem sorta crazy to me but definitely full of awesome potential. I thought I would give a brief introduction (abridged from the Wikipedia) and some particular ones that I found fun.
A Thangka is a Tibetan silk painting depicting a Buddhist deity, event, or mandala. It consists of a picture panel which is painted or embroidered, over which a textile is mounted, and then over which is laid a cover, usually silk. Originally very popular among traveling monks because they were easily rolled and transported from monastery to monastery. Thangkas served as important teaching tools depicting the life of the Buddha, various influential lamas and other deities and bodhisattvas. One popular subject is The Wheel of Life.
Devotional images act as the centerpiece during a ritual or ceremony and are often used as mediums through which one can offer prayers or make requests. Overall, and perhaps most importantly, religious art is used as a meditation tool to help bring one further down the path to enlightenment. The Buddhist Vajrayana practitioner uses a thanga image of their yidam, or meditation deity, as a guide, by visualizing “themselves as being that deity, thereby internalizing the Buddha qualities”
[feel free to add any of your favorites in the comments. Or to mail me any extra you have lying around…those damn things are expensive. My meditation deity is Manjushri and/or Henry Rollins]