Chimester - (formerly TreoHour) will remind you of the passage of time, it has several user configurable options and a built-in popup clock and keyguard to give you a unified view of the device status.
The clock displays the alerts, sound, message, email, battery level, tasks and appointments status.
Cool tabbed user interface.
Device status display - pending alerts, volume status, new message counts, new email counts, pending tasks count, upcoming appointments, battery level.
Launch applications from clock display.
Use system MIDI tones for chimes.
User-configurable keyguard unlock buttons.
Added no-timeout option to popup. If selected, the clock display will be displayed till it is manually dismissed or auto-poweroff kicks-in