Best to-do management
Despite the fact that online service costs 25USD per month, RTM is best to-do management system I used (and I tried all of them). It syncs well with all devices, with Outlook, and tags and notes are integrated with Outlook too. If you can afford 25$ per year, and have busy schedule I strongly recommend it..
Adnan MO about
Remember The Milk: To-Do List, v2.0.1