Yesterday we've created wireframes for the fist ToDo list concept. The main ideas is to have 3 areas for Today tasks, Tomorrow tasks and Later tasks. Use drag and drop to plan tasks for today or move them later. No calendar view, just plain list with 3 groups.
There were debates around Tomorrow tasks. Several people think that this group is not required and Today/Later will be sufficient.
Also this ToDo list provides an ability to see other people's ToDo list as well as group tasks by various parameters. Time grouping is default (Today/Tomorrow/Later), but also it is possible to group by User Story, Project, Type or other properties.