In 2008, I DIED. My personal assistant, Sandy, from http://iwantsandy.com was retired when the project was gobbled up by Twitter.
For those who haven't had the pleasure of meeting Sandy... she was a personal planning assistant who functioned primarily over email (but also twitter and web interface). She was helpful and not annoying.
You could forward emails to her with simple lines at the top like "remind me to pick up the kids next tuesday" or "r call my boss in 23 days" or "r revisit this email in 1 year #review , #2011-plans".
She would let you know if she didn't understand, but most of the time she did. And she would send you reminders, with the original email attached so you can see what you were looking at when you made the reminder. She'd also deliver daily agendas if you wanted them.
She understood most commonly expressed forms of time, recurring events ("r take out the trash every tuesday morning" or "r pay netflix every 90 days") and you could look at her calendar to make adjustments if you needed to move something.
I depended on Sandy and I never found a good replacement for her.
RTM handles emails to some degree though it's far pickier about how you phrase things than Sandy was and not nearly as simple. I also dislike how it does reminders and dislike its web interface.
I've also been playing with Springpad a lot but it's rather short on planning features.
Has anyone found anything like Sandy out there?