After 626 miles of completely enjoying riding Sweetpea, I did notice that the chain might need cleaning. That accomplished (also the Brooks saddle relaced with something a bit more durable), I then added Sweetpea to The Book.
After I built up Bleriot, I realized I'd have to start really keeping track of when I cleaned chains, replaced parts, did major maintenance, etc. And, with two (at the time) bikes, I'd better write it down somewhere!
Hence, The Book. Each bike has a section, and, other than date and odometer reading, it is pretty free-form. I like to know how long my wheels have lasted, how many miles are on a tire, when did I last change a chain (or for that matter, clean one :-) ). I'd be even better if I noted when I swapped out the batteries in the blinkies. (note to self...)
There are 4 bikes in the book - Bleriot, Lemond, Sweetpea, and Gitane, with Bleriot having the distinction of two full pages.
I've got to wonder how the folks I know with, um, many (15, 50) bikes keep up with it all...