One of my favorite things is book covers--it's funny how you can get so used to a certain cover that reading the same book with an updated one makes it feel like it's not the "real" book. The new book covers from faber & faber are a whole different story though--aren't the awesome?
Last year penguin also re-released their classic books with new covers, which are stunning. I love the colors and there is nothing better than a matching series of books in a row.
Some book covers that left a mark on my brain are the copies of my sister's Narnia books that she had--you almost never see these covers anymore, but I love them.
This James and the Giant Peach book has the most beautiful illustrations ever. At one point our copy disappeared but a couple of years ago I was able to find a replacement on Ebay. Hooray for Ebay!