Does it need to be desktop based?
I do exactly what you are describing with my android phone clock/alarms. I have about 15 alarms setup to hit me throughout the day/week.
Since I carry it with me always, it makes for the perfect device for just such. It can use different sounds or even songs, can control the volume, etc.
I use the standard features built into the phone itself which seems to work great, but I am sure play.google.com has a ton more alarm apps too.
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