One Day by David Nichols

I loved, loved, loved this book.  I am not sure if it spoke to me because a) I would be around the same age as the main characters so I could really relate to the setting (except that it was in London and I, ya know, grew up in NY) or b) I have a friendship *similar* to the main characters. 

Apart from that I loved the structure - each chapter is on the same day a year apart.  So when the chapter ends on a cliff hanger you don't find out what immediately happens, you can surmise by where they are a year later but you don't get the full details - love that!  I have described it as a smarter chick lit novel.