Combined with dropbox or some other remote storage and sync tool across multiple devices, this works wonders. There is an org-mode app for mobile devices as well. Of course people who dislike emacs might have a problem but it's quite hackable and there is nothing to keep one from associated .org files with emacs and using emacs just for todo lists (theres only about 5 or 8 commands in org-mode that you really have to know to be effective).