Although a book's cover may not be able to ultimately sway my final judgment of its contents, a nice cover (and my tastes are varied) will pique my interest enough to pick it up and leaf through it, to discern whether or not I'm up for the commitment.
The Book Cover Archive recognizes the need to appreciate this artform and have began posting covers of all sorts. I hope the appreciation continues and flourishes as we enter an age where more and more books are becoming digitalized, and where the experience of holding a physical book while reading, something that you can smell and not only touch but feel becomes less cherished by many. How anyone could choose to read a book on a Kindle or computer screen is beyond me, but that's another story.
Here's a small collection of covers I fancy.