I'm a student pilot and am thinking about putting a tasteful decal on my log book, if for no other reason than to identify it as my own. Is that OK, or would that be frowned upon? Thanks.
I don't belive there is any regulation against it. Keep in mind you may need to show the book to officials at some point so keeping it professional is not a terrible idea
(1) Persons must present their pilot certificate, medical certificate, logbook, or any other record required by this part for inspection upon a reasonable request by -
(i) The Administrator;
(ii) An authorized representative from the National Transportation Safety Board; or
(iii) Any Federal, State, or local law enforcement officer.
The FAA is more concerned with what you log than what's on the cover of your book. I can't say I have ever seen a log book with a bedazzled cover but I'm sure they are out there. If you are talking about putting a decal that says "Ryan's Log Book" across the cover, that's fine, but a giant glow-in-the-dark unicorn sticker might get you some looks although technically OK.
My mother used to wrap my books when I was a kid in school for me. I don't know much about aviation and how this logbook looks, but maybe it's doable to use some kind of a "protective cover" that can be taken off anytime, in case you have to show it on official occasions?
Beside making your own from book protection paper, kitchen shelf paper, newspaper or non-sticky plastic foil, you can buy pre-made covers in different sizes. Have a look at a stationery shop, bookstore or at a school supply store. The foils and pre-made covers are available in transparent and different colors and with or without printings (for example maps).
It all depends upon how your logbook will be used. If you expect a professional career in aviation, then I would keep it within the envelope of what that community would expect.
Another thing to consider, you can have multiple logbooks. For example, I have a separate book for gliders, glider towing and rotorcraft. When instructing, I keep a lesson record, which covers instruction details, evaluation and logged times. Those are summarized on a spreadsheet which I update periodically. My work flying and my personal flying have separate logs as well.
The FAA inspectors seem happy with my record keeping and appreciate the segmented logs. Things like night currency, instrument currency, glider currency, are recorded in the rear of the books and can be carried from book to book.
My multiple logbook implementation is not for everyone, but I mention it because if one wanted to have something radically unique, you might do so in a separate book. As an example, early in my flying career, I noted the names of people I took up on rides, or had them sign my book. Later, I decided to stop that practice when a significant other started reading the logbook.
But to be clear, your logs need only be a reliable record which you can readily use for FAA compliance, negotiating rentals, employment or whatever. Many pro pilots I know used spreadsheets, and their company issues a record for company activity. Similar in the military.
In summary, do what you want, but you may wish to maintain a more conventional presentation if you expect to be pursuing activities where your logbooks might get reviewed for employment or other activities.