OmniGrowl is an expandable framework for sending Growl Notifications for applications that do not natively support Growl, generally which have to be polled for changes.
Features:
Built-in support for upcoming iCal events, To-Dos, Birthdays, etc
Built-in support for Address Book Birthdays
Built-in support for iTunes track changes (off by default)
Source code included, expandable framework
Requirements
OS X 10.4 or later
Growl
Universal Binary
Author's Site
MajorGeeks TX
Internode