Called in at Starbucks Meadowhall at lunch and saw the pick of the week app promotion is the popular Sleep Cycle Alarm Clock iOS app. I've used this app for over a year and find it pretty useful. App retails at £0.69, always seem to be feature on top 10 app list (currently #6).
Details of app can be found on my post below.
The pick of the week cards are usually found at the end of the counter where drinks are served, each card has a unique code which you need to redeem at the Apple app store. Assume its a national promotion but can't be certain.