Caramel Cloud has released Notificant for Mac OS X. The software is available for $5 through the Mac App Store and works in conjunction with a free Web service.
[ad#Google Adsense 300×250 in story]Notificant is a “cloud”-based service that syncs and delivers reminders and notifications on an unlimited number of Macs connected to a single Notificant account. You can sign in from the Web site from any computer, then send reminders to the Mac or Macs linked to that account.
You can specify which computers should get the reminders, set a notification schedule, customize the notifications using different sounds, and more.
Notificant requires Mac OS X 10.6.6 or later.