ZenFriend looks like a good one, but before I saw your post I had already purchased Serenity (two bucks), and this morning I tried it out.

Serenity

Serenity is more configurable than Mind, offering a generous choice of sixteen different sounds. Some of the sixteen don't seem that usable (didgeridoo, anyone?). The default of singing bowl #1 worked fine for me.

You can configure the number of strikes of the sound. I put two strikes of the singing bowl at the end, so that the first strike would wake up my powered speakers, and the second would be audible. The sound of the singing bowl lasts longer than five seconds, so I actually get the tail end of the first strike and then the full sound of the second strike. I turned up the volume on the speakers louder than I usually would, so that I got the volume I wanted.

Serenity also allows an "interval" sound and a "cool down" sound. These are not things I would use, so I set them to silent. The app has four presets where you can set up patterns you commonly use. I found it a bit confusing switching between the preset selector screen and the main screen, as the main screen doesn't seem to mention which preset you are using.

I did notice when I was testing it that the screen stays lit up all the time (i.e., doesn't go to sleep). This wasn't a problem, since the app didn't seem to have any appreciable effect on the battery.

Overall, I would say that Serenity works quite well for me.

I didn't even know that was there. I tried it for the first time this morning. It certainly has both the functionality and the simplicity I'm looking for. But it definitely sounds like an alarm clock when it goes off.

For an extra two bucks, I prefer the singing bowls. I don't begrudge app developers their two bucks. I'm sure it's a lot of work to produce something functional and esthetically pleasing.