I need to take a small break every 15 minutes when using my computer. I looked at various timers for OS X to help notify me when 15 minutes were up. I wasn't overly impressed with any of the options that I found.
Then I stumbled upon a neat feature in OS X that will announce the time every hour, half hour, or quarter hour. To enable it, go into
System Preferences, then
Date & Time. Select the
Announce the time check box and the desired interval.
You can also change the voice for the time announcement by clicking on the
Customize Voice button.
Though this solution isn't perfect it seems to be working well for me. The only catch is that in noisy environments or when I have the audio off I can't hear the notification.