I'm a big user of TODO lists. I generally keep a text editor open with at least one todo.txt file (either general or project-specific).
It would be nice to have a website to manage these lists of tasks and use them to help manage time and generate schedules. The schedules should be quite informal - each item should fall into one of three categories - tasks that should take less than a day, tasks that will probably take more than a day (and should be further broken down to get an accurate schedule) and tasks that have not yet been placed into one of the previous two buckets (more details on this costing algorithm).
The site should also have the ability to suggest the next task and allow the user to create dependencies between tasks (e.g. A must be completed before B can be started).
[...] other similarly impactful change I want to make. Rather than adding the second refactoring to my TODO list and continuing with the first, I’ll go right back up to the top of the program and work my [...]