The first Windows 8 Alarm App KoAlarm debuts in the store. The App looks polished, but basic. Just to say, it gets the job done. You can chose to be alarmed by time of day or weekly, you can also choose the Countdown timer function. There are 6 Alarms or Timers to choose from. This is a welcomed addition to Windows 8.
Letop: You may have to search for this App using the Search Charm, as it is not visible in the store at the time of this writing.