To-do lists range from minimalist to impossibly intricate; this app can be either. Type an errand or idea in the Add Task bar and view it in an easy-to-read cloud-based list on your device or the website. Make project-specific lists, assign tags and priority levels, and set due dates. Push reminders require a pro account, but email, SMS, and IM reminders are free. Plus, there's no shortage of ways to survey your to-dos: View lists individually, scan all items at once, or check out a calendar view of upcoming tasks.
WIRED Sync service keeps tasks current across devices. Enter items sans menus using "Smart add" syntax. Set default list for sorting new tasks quickly.
TIRED Doesn't let you order lists manually. Free version syncs only once a day.