There is a lot of of calender software out there, to do list software, task list software, alarm software.
And it is all disjointed. I will receive an e-mail in my Gmail, copy and paste its body into a Google Calendar entry, then start a Google Document, send the URL to my work mates through e-mail, then finally paste the URL to the calendar entry. Even working within a single constellation of software, my workflow remains jittery. As the information is copy-pasted around, I am responsible for keeping everything in sync.
I might as well use my inbox to keep track of my tasks. At least there, I can see everything at once. Which is what everybody ends up doing.
I am quite excited about the Chandler project. In their system, an e-mail is a calendar entry is a to do entry is a document. Which is a how it should be.
Chandler is sprinkled with the "getting things done" spice. Items can be either active now, deferred or done. Deferred items can have a tickler alarm, which naturally goes on the calendar.
It also serves as a sharing platform. You share a document by e-mailing the URL to it. There is no needful further login, knowing the URL is your password.
It seems like modern lessons in interface design were finally heard. I will try using it. Ask me how well it went in two weeks.