One of the most popular free medical apps on the iTunes app store is "iCare Health Monitor–can measure blood pressure." Without any attachments it claims to measure blood pressure, heart rate, blood lipids, blood oxygen, vision, colorblind, hearing, lung capacity, breath rate, and psychological index! If you believe all that, I have great view land to sell you in Florida! If you are tempted to trust your health to this magical app, read this careful review first.
PositiveTip: Even if it is in the Top Chart, buyer beware!