Dublin-based graphic designer Niall McCormack runs "Hitone: Vintage Irish Bookcovers". The site features bookcovers and more from the Irish state's first 50 years. I found so much awesome flipping through just a few pages of Niall's posts. Here are a few of my favorites:
I also love the simple design of the site itself.
If you have hours to spare, I recommend browsing the archives at Hitone.