Oak is a community-driven guided meditation and breathing exercise app. Our meditations were built from data gathered in-app as beta testers completed their sessions (or ended them early). This led to hundreds of adjustments in pace, tone, and verbiage. We're geeks: Support for pre/post heart rate tracking (and variability) soon.
Meditation Studio is a powerful, mobile-first meditation app. Enjoy. :)
SelfMonk is a Voice App that gets you meditating in less than 4 seconds.