ReRemind is a simple Windows Mobile service that will play a sound at a specified interval when an event is waiting your attention. This is particularly useful for devices that lack standard amber/green notification LEDs (like the Diamond / Touch Pro), but can be used with any WM device if you want audible notifications.

Changes:

V6 – Added support for standard devices to use the config app (untested); Fixed a bug where some pre-6.1 devices detected as 6.5 devices, leading to alarm notification problems.

http://forum.xda-developers.com/showthread.php?t=498161