In the course of planning how I'll run my personal organisation system next year, I've had to do some thinking about whether to use an online calendar, or continue to use a paper one. In my job, which involves a lot of travel and external meetings, I need a portable calendar which contains not only my appointments but also the information I need about them (ie who is attending, their contact details, maps or directions for getting there, etc). I also need to be able to make new appointments on the spot - I hate having to say "I'll need to check my diary when I get back to my desk" - so my diary goes with me everywhere.
There's no reason why I couldn't use a PDA for this, in fact I've done so before. This gives the benefit of being able to synch information from your desktop computer to your portable one. But to be honest, I return to the paper diary because I prefer to write notes in my diary to having to synch the PC and PDA, or update a PDA with it's fiddly little keyboard.
More recently the ability to share invitations and events via Google Calendar has gotten me using that for planning joint events, so for 2008 I plan to use Google Calendar for joint events, and my Moleskine for planning my personal day to day schedule.
So will you be an electronic or paper diary person in 2008? Do you use a blend of both? Share your system in comments please.