I keep all of my old calendars.
You may think that's weird, but I really enjoy looking back at what I was doing on October 1, 1998, or flipping through my schedule in 2002.
(I don't look at it every day, of course...just now and then it's fun to take a trip down memory lane.)
At some point I realized that I'd migrated my calendar life to an electronic form - in 2006. There was definitely a need to save that information so I could look back on it.
As proof that digital doesn't reduce the use of paper, I printed each month out, from 2006-2012, and put them in a notebook.
And that notebook now lives in a closet with my other calendars.
Somehow, it just feels like all is right with the world.