In my search for a nice and simple software clock with chime I found ClockSmith Lite. It’s available for Windows and Mac. The chime is really nice and can be set to play quarterly, every half hour, hourly, or it can be turned off.
I have set the chime for every half hour in order to use it with The Pomodoro Technique. At the chime I take a five minute break, then work for 25 minutes until the next chime.
The tolling of the hour has an on/off switch. I use that tolling as a reminder of the 18 Minute Plan That Keeps You Focused.
The creators of ClockSmith Lite are Dharma Gaia, I like their description of the name:
Our name reflects humanity’s responsibility to care for the earth and her inhabitants. It is derived from word Dharma; a Sanskrit term encompassing universal law, harmony, and personal duty; and Gaia, the ancient Greek name for the Goddess of the Earth.