So small and doesn't get in the way of anything, but is packed full of features. I tried it for a couple of weeks, and it was so useful and fleshed out iCal so much that I decided to pay for it. It would be great if Apple integrated this sort of thing into iCal - a dockling/menu bar option that floats your To-Do list somewhere, works with alarms and birthdays from the Address book, but I don't know if any big improvement is coming in Tiger.

This rocks and it makes iCal more attractive to use too.