When signing books, or sending bookmarks to our favorite booksellers, the cost of 4-color can be major, this added to whatever else promotion necessary. In times of higher postage, we will likely be sending less mass mailouts and more Internet, yet as a hand-out promo, you can't beat a signed bookmark with all the information on it, including website, blog, storyline, etc.
These are bookmarks made from postcards. With online postcard deals coming at us all the time, I simply took postcards and took them to a local printer (someone I do business with all the time), and he cut them in half. Voila! Bookmarks.