Go to DBT Self Help and to the section called "instant Mindfulness". That section contains short, guided meditations that fit the bill. It also has an entire series of DBT lessons you could work on your own if you wanted. There is also a social group here specifically for mindfulness. I know a blog address was recently posted there that was filled with mindfulness stuff.

An exercise you can do on your own. Do a chore around the house: vacuuming, the dishes, etc. and stay mindful as you do it. Tell yourself what you are doing as you do if. "Picking up the sponge", "dipping it in the water", etc. Also, pay attention to the physical sentations associated with what you're doing: the warmth of the water, the feel of the soap, the coolness of a glass, the smell of the soap, etc. When your mind wanders, which it WILL do, just a knowledge that it has and draw it back to what you're doing. Don't punish yourself, just return it to the subject at hand.

I hope these help. Feel free to pm me if you'd like more ideas.