I've always used To-Do lists in one for or other and have been through a broad range of offerings over the years, never really settling on one in particular for sustained use, until I stumbled across 'Wunderlist'. It was so small and simple I never thought it would hang around past the statutory 'install and evaluate' 15 minutes most new software usually gets (if that) however it's still in my dock, and still in daily use almost a year after download.
Developed in Germany by Berlin based startup 6WunderKinder, Wunderlist has been nominated as web app of the year, and rightly so I say for it's a joy to use. It works seamlessly, it's completely cross platform, and, it's FREE. What's not to like?
As intuitive apps go I don't think there's much to beat it. List and contained task creation couldn't be more straightforward and with combined scheduling plus related cloud sync to the online version and/or all your devices you can empty your head, pull back contents, and get reminders from anywhere at anytime.
The icing on the cake for me is the amazingly simple share facility offering real time task list collaboration amongst other Wunderlist users. Click the list sharing icon, type a user email(s) and send the invitation, superb, although sharing my 'Jobs to do around the house' list with Lesley might have been a mistake as it quadrupled in a matter of minutes, damn.
Wunderlist is available via the App Store for Desktop, iPhone and iPad, or for those of you with 'other types' of computer (or Android devices) download from HERE.