Pill Reminder is a quick and simple app to help you remember to take your medications or vitamins. Enter the days and times you have to take your pills and then simply let the unobtrusive menu widget (and/or a floating pillbox window if you choose) alert you when it is time to take a pill! It even logs when you've taken each pill.
Requirements: Compatible with 10.7 or later (OS X Lion). Requires Mac App Store. Internet connection required for download.