Everybody, who doesn’t live behind the moon, must have some kind of electronic calendar nowadays. Running around with a small note book and a pen looks very oldschool, PDAs are on the market for ages already, mobile phones with extensive PIM features as well. While I don’t use a PDA, at least I store everything in a simple text file on my computer, using the Emacs diary-mode.
Google opened its GoogleCalendar as well some month ago. So it seems PIM reached Web2.0 now and why not give it a try.