This morning Geoff pointed me in the direction of The Book Cover Archive, which is a truly lovely thing. I am not ashamed to admit that I have picked up books because I loved the covers.
I am not in any way a design snob, but I do love how you can browse by typeface. Here are some book covers that feature a favourite typeface of mine.
The above is a personal favourite, both from the archive and from, well, the canon of English literature.