I carry my 15 year old leather Franklin Covey with monthly inserts. I fill it in as I get booked. I carry (4) updated xcel forms:

(1) 2008 bookings
(2) 2009 bookings
(3) master 2009 account list (my work of art)
(4) unpaid invoices

Works perfectly. Very easy to plug in new jobs in the proximity of exisiting ones.