There are sooooo many effects that utilize a DB. In fact, my rendition of Cannibal Cards (found on this site), may or may not use a DB. Lol.
Also, with the post just made about the Hyper Card, you should check out Daryl's Hyperbentalation. It uses the Hyper Card technique along with a double backer and double facet to create one of my favorite pieces of magic...