BB Samrt Alarm:
Costs $15 but by far the best alarm clock available on mobile device, I only use this one. It can store multiple alarms, you can select exactly which days you want it to ring, and you can also make a quick alarm like say u just want to take a 3 hour nap, you can set a quick alarm for 3 hours and that's it, its really simple to use, and very customizable.

Download Trial (Once purchase it becomes full version)

Download Full (Requires purchase to use)