Check out the detailed review by Dan Cohen on ToDo for iPad
"In all, ToDo for iPad is a gorgeous application that is as functional as it is nice to look at and use. It works perfectly, has numerous ways to customize both the look and the function of the app, and it is the best task manager for the iPad bar none."
ToDo for iPad is currently available for $5 and requires an iPad running iPhone OS 3.2 or higher. That's cheap considering the iPhone version is 10 bucks!