I'm currently reading Ian McEwan's Atonement, I'm about a third of the way through and I love it. I bought it from a charity shop for 99p a couple of weeks ago. I watched the film years ago so I've wanted to read the book since then.
From the film I remember it having some dark subject matters but also some romantic aspects, so it's not all depressing, and it has some amazing description and detail. The reason that I think it's a summer book is because the first part that I've read so far is set on the hottest day of the year, in uncomfortable heat, which adds to the uncomfortable awkwardness between some of the characters. So if you read it in the summer you can understand the feelings of characters more clearly.
I love finding books in charity shops because I don't look for anything in particular, just things that I've heard of before, but that also means I end up coming home with about 4 books every time.
What's everyone else reading at the moment?