Bling, swag, stuff.
Whatever you call it. It's the stuff that you hand out to, and display for your readers. It's supposedly there to help promote and remind the reader of who the author of the book they just bought, or want to buy is.
What am I talking about? Bookmarks, business cards, promotional items, etc.
To be honest, you don't need it. However, if you want to be remembered, chances are this kind of stuff will help. It's a way to remind someone who is interested in your work who you are and what you wrote.
One thing to think about when ordering bling, is what you wrote and are promoting, VS what you will write in the future. Imagine it this way. If you are going to write a series of books with the same feel, ordering a thousand business cards in the same style might not be a bad idea.
If you write five stand alone books in quick succession, ordering a thousand business cards with your first book cover on it is probably not a good idea.
Or if you're like me and run the gamut of genre between futuristic suspense to middle grade non fiction, book specific items are not the best idea for most of your stuff. I also imagine that some promotional choices can and should be made based on the amount of money you have to promote your books. I honestly can't go out and buy new stuff like banners for every book that I am producing. Nor do I want to. What's the point of having a closet full of items for past books?
On the other hand, book specific book marks are a good idea. Whenever someone buys a book you put a few in the book, or in the envelope or sign them and hand them out to people who don't buy your book but look like they might be interested later.
If you are displaying your book(s) at a conference or signing it's a good idea that the table reflect the book. Even if you have to split the table and use two themes. Another option is to create a general look that does well with all of the books offered. I imagine it might be as hard to do as it seems. Unless all of your books reflect your theme or genre.
So in retrospect this is what I think should be done in regards to extra stuff.
Banners, signs, business cards, e-mail signatures, author pictures, author bios, website themes, (unless you are doing separate websites for every book, genre etc.), display tables and how an author presents themselves, all need to be more generic.
book marks, book related giveaways, things like pens, key chains, pins, decorations for tables and for launches, can be more specific.
Authors note: these promo items can also be ordered in smaller amounts and still be affordable. However, spending lots of money on large items for every new book can cut into profits that could be used somewhere else.