I forgot to mention that I use an appointment book as well. got it at walmart for $20, it looks to be leather on the outside and zips closed. I also use it to double check to make sure all my portraits are in the finance spreadsheet and it holds my customer info sheets I use for picture viewings for sessions that I havent done yet.
I just use google calendar for reminders. Like if someone tells me at the beginning of the summer they want an autumn portrait Ill put a reminder in there for the first of sept and its easy to move the reminder back yet if its not near fall yet.
Ive played with the calendar on my new ipod but its a bit annoying to use the small keyboard with my not so fat fingers. Plus its easier to loose than my appointment book.
Gerry, try getting a stylus to use with your Ipad. I love using it over my fingers. Plus, I just started using a model release app and signing with a pen is much more professional looking. Its also a lot easier to make a "real" signature vs. the slop I get with my finger.
Also, you can always auto sync your ipod/ipad so that you could never lose your appts.