todo app idea: A hierarchical list, somewhat like nautilus, which shows folders which can be expanded to show their contents or double clicked to make that folder the top-level. Each item and folder has: - a name - one or more tags? - optional password-protection (possibly one password used for all password-protected folders, and the folder just has a flag to say it's protected) Each item in a folder has: - a date or date range (optionally including time) - contents (free-form text) - a 'completed/not completed' flag Each folder has: - an item sorting policy (manual, by date, by name, by completion etc) - if manual sorting, then some options to rearrange by date, name, completion, etc. Both items and folders can be set to notify you at certain times. A folder with items corresponding to christmas gift ideas can be set to show up in the notification bar each year from november to december to remind me continuously, and can't be cleared. Notifications can be set to show continuously for a period of time, or be set to go off at a certain time, causing a vibration, and can be cleared from the notification bar.