Mark of Athena by Rick Riordan.
This was book 3 in the Heroes of Olympus series. I got so into this book that by the time I got to the end I forgot that this was not the last book in the series. I was upset that there was more to the story that I'd have to wait to discover until the next book comes out!
Cold Days by Jim Butcher.
This is the latest book in the Dresden Files. I've always enjoyed the Dresden Files books, although some of the books in the series are more enjoyable than others. I thought this one was my favorite, next to the first book of course. All I can say without giving too much away about the plot is that Santa is one bad mamma jamma.