A utility that lets you enter iCal todos via a window that pops up when you hit a hotkey. Free.

"TaskPaper is a simple to-do list application that helps you stay organized. Unlike competing applications, TaskPaper is based on plain text files which offer you paper-like simplicity and ease of use."

"Event Maker is designed to be a streamlined way of taking e-mails from Apple’s Mail application and creating iCal calendar events from them."

Dinky little todo list application, integrates with the Finder, Address Book, iCal, Quicksilver. (On closer inspection, a bit shit)

High Priority is an inexpensive Mac OS X 10.4 or higher menu extra whose sole purpose is to help you manage your To Dos in a simple, intuitive, and pleasant manner.