Todo is great at talking to other online and desktop to-do-list. Sync your web-based lists at foodledo.com or rememberthemilk.com, or use Appigo’s free software to sync with iCal for Mac; similar software is planned for Outlook. Other features you won’t find in things: Sub categorize to-do-lists; label tasks with tags, priorities, or contexts (in Things, you use tags for all three); add repeating tasks like monthly rent or weekly trash pick up; get alerts when tasks are due; and customize list colors, completed task graphics, and priority icons. Especially cool: “task types” let you turn to-dos into one-tap action to call, email, or map a contact.