Here's my Top 5:
- Pulse Oximeter:
Oxygen saturation is a key metric for medical analysis. For example the result of sleep apnea can be seen as a drop in oxygen saturation and many other dysfunctions surface through that metric. It's also interesting for fitness and sports in general and some fitness trackers actually provide this data already.
The Microsoft Band measures the heart rate optically using a photo detector and this is the same principle used for Pulse Oximetry, so the sensor is already there. I think it's just a matter of adding the right algorithm and surfacing the data in Microsoft Health.
- Sleep tracking Precise mode:
I would really love if the Band's sleep tracking had a Precise mode which would take samples more often during a night and was allowed to run down the battery in 8-10h, so I can decide when the precision-battery-tradeoff is applied.
- Re-occurring alarms:
The vibration alarm is awesome but it needs to have a feature so it can be made re-occurring. The Band could just sync with my Windows Phone alarms but should also work when the Band is not connected to the device via Bluetooth.
- Smart alarm:
Although the sleep stages are not 100% reliable it would still be good enough to wake the user up during a certain timeframe when the sleep is not Restful anymore. Lots of fitness trackers provide that feature already which actually have less sensor data.
Currently the Notification Center and Mail tiles stay at the count until the tiles are opened. This is rather annoying as it is another notification hub which needs to be cleared in addition to the phone. I'm sure it's a technical challenge with the WP APIs but for vNext it would be great if the Mail and Notification Center tile count would also be synced over Bluetooth when those are cleared on the phone.