MSentinel is a free application coming from XDA Developers that will remind you of those system events which you have not acknowledged.

After downloading and installing to Device, the first time you run the application it will bring up the configuration window where you can set the interval for the checks, the sound of the alarm, whether to vibrate or not and what type of unacknowledged events to look for. After all your settings are set, Save and execute and MSentinel will stay memory resident checking for events at the interval specified in Settings and alerting you if any.