I can't endorse this service strongly enough. I've been a daily user for nearly a year.
Todoist provides a way to organize, plan, and track your tasks.
It's the lightest version of project management that you can imagine... and therefore, you will actually use it.
Tasks are organized in a project hierarchy. For example, my hierarchy looks something like this:
Administrative (Example "Send quarterly report for grant on January 5th")
Finances (Example "Double check the automatic payment for the mortgage on January 25th")
Seasonal Maintenance (Example "Vacuum behind the refrigerator every six months starting October 1")
School deadlines (Example "Pre-pay school lunches every 1st day of every month")
birthday party gifts
Teacher gifts (Example "Find end-of-year teach gift May 15th")
Go for a hike!
Each task can be scheduled (and rescheduled), not just for a future time or date, but also for smart recurring intervals, like "Take trash out every Wednesday" or some of the examples above.
You can view the tasks in each project, or you can use the 7-day view, where tasks are organized by day... overdue first, then today, tomorrow, and the days stretching out for the next week. You can see what's coming up, but also stay focused on what you need to do today.
While many people would say that if they wrote down everything they had to do their brain would implode... I have found the opposite. I can now walk past a lot of "to-do's" in my house and quickly dismiss them. They are either already scheduled for a day when I actually have a chance of completing them, or I can honestly say there is no hope of getting to them. Todoist definitely helps me "get real" and that releases a lot of stress.
Knowing that I won't arrive at school on the last day and realize I forgot to get the teacher and end of year gift is peace of mind. Knowing I need weather stripping for a home maintenance chore scheduled for next weekend means I actually get the weather stripping when I'm at Ace... efficiency! Looking at the list and deciding which task is really most important means I don't waste time on one thing (like a blog post) when I really should be doing something else (preparing for Friday's presentation). : )
OK, with that, it's time to move on to the next task - and now I can check the box next to: "Promote Todoist on blog on Sunday"