No one is going to be able to suggest something actually relevant unless you give a better idea of what you're interested in. A good idea would be to post similar titles to what you're looking for.
Personally, I'm spending the summer expanding on my philosophy background. I'll be doing it by taking a course for free through podcasts [several big name schools have nearly all of their courses recorded and available for free on their department websites, Berkeley and Oxford for sure]. What I've done is gone to the department websites, gone through the classes, and found something relevant, then downloaded the syllabus to see what materials I'll need. I can then take the course through podcasts while reading through the material. I think I've settled on a class by Prof. Dreyfus at Berkeley on Heidegger.
You can use this technique for expanding your education on any subject. All departments let you do this and have full webcasts of the lectures available online for free. You don't even have to do the whole class, just find a course that covers a text you want to learn about and use those webcasts as a resource. There is something to be said for reading through something and coming to an understanding of it on your own, but you honestly gain way more through the insight of someone well versed in the subject.
Then again, if you want something a bit less stiff and educational, I've recently enjoyed The hitchhikers guide to the galaxy, Ender's game, The once and future king, All things shining (FANTASTIC book by Dreyfus, the professor whose course I'm taking, about secular spirituality in the modern world, but has a heavy basis in ancient western lit ie oedipus, the odyssey, dante's inferno etc... very accessible even if you haven't read these though), Voltaire's Candide (Awesome read even if you don't like phil), and the alchemist... I'm just throwing titles at you at this point. PM me if you'd like some suggestions a bit more focuses to your tastes.
BTW, if you want something more science focused, I would recommend doing what I suggested above about taking a podcast course, but take a seminar type course that discusses scientific papers focused on a topic. The lectures will be interesting and stimulating, and you'll be able to review a good bit of science.
