There are many apps and websites which have been developed to help one cultivate a mindfulness meditation practice. Here are some of my favorites:
Headspace is a website and app that has been developed to teach anyone how to practice mindfulness meditation, at their own convenience and pace. This resource provides information regarding how and why building a mindfulness practice can help, in a concise, easy to understand manner.
Stop, Breathe & Think is a free app that generates a list of mindfulness meditations based on how one may be feelings at any particular time. The guided activities are relatively short (3-7 minutes) which is a great way to sprinkle in some mindfulness during the day.
OMG. I Can Meditate! is another free app. The app provides meditations for families, including children and teenagers, along with meditations for specific areas, such as relationships, happiness, etc. This app also has a cool feature that allows one to wake up to soothing music or to set an alarm for your meditation practice.