To-Do's Screenshot from Basecamp

Use the To-Do section to make sure all the little things get done. For example, a list might be titled "Bugs to fix on the home page" and include items with checkboxes like "Colored bar doesn't display on old browsers" or "Revise the welcome text" or "Try blue instead of purple." You can create as many lists as you want and each list can contain up to 1000 items.
Screenshot highlights

1. All of your lists appear in the sidebar for easy access.
2. Client view: Clients will see a red dot next to open items and green checkmarks next to completed items.
3. Your view: You'll see checkboxes — check off an item to move it to the completed section.