mysleepbutton – www.mysleepbutton.com
I often use this to help me fall asleep, can't recommend it enough.
My mind has trouble turning off, I have big trouble falling asleep. This app sounds silly but works for me, it just reads out random words for you to 'imagine' and 'think about' ever 15 seconds. Doing this tricks your mind to stop thinking about your life and worries and you fall asleep.