This has been floating around the internet for a while, but it's good to come across again. I'm impressed by the level of simplicity to which the technique has been distilled. Notice that it wasn't necessary to write a book about the productivity system — it can be explained in a paragraph.
On a side note, I believe there are a number of iPhone apps that implement this system.
> On a side note, I believe there are a number of iPhone apps that implement this system.
I can verify this. I use Streaks, which may have been the first one. It has support for multiple calendars (for different goals), which kind of breaks the simplicity of Jerry's approach. I might cut it down to one calendar/goal.
On a side note, I believe there are a number of iPhone apps that implement this system.