I really, really enjoyed this book--and I generally avoid 1) cancer books and 2) books about popular girls--especially from new-to-me authors (this is a debut). And Send Me a Sign has both. But, it was incredibly fresh and an emotional novel that surprised me. 
 Mia is a super popular cheerleader with a perfect life (seriously--in the first chapter, I was all, "I'm not sure I can spend 300+ pages with a super popular cheerleader, those girls hated me in high school.". Her friends has the perfect summer before their senior year planned. Except Mia is diagnosed with leukemia. But, she doesn't tell anyone. That is, she doesn't tell anyone except her neighbor Gyver (yes, like MacGyver), who's a childhood friend. He's there for her during her stay in the hospital and is all around wonderful. 
 After she returns home following a month in the hospital and having successfully concealed her illness (egged on by her mother in a sadly realistic case of WTF denial), she continues her deception, while being pursued by The Jock aka Ryan. There are lots of complications in their relationship, and even though Ryan wasn't the guy that I wanted for Mia (obviously her sweetie pie musician neighbor Gyver is the boy you've got to root for), I LOVED that Ryan was never portrayed as a bad guy for the sake of Gyver being the boy for Mia. Does that make sense? Both boys' reactions to dealing with Mia's illness rang authentic and it made me care about each of them. 
 I also was very intrigued by the parental dynamics in SMaS. Mia's mother becomes obsessed with hiding her illness, pretending that everything is normal, while her father is obsessed with accumulating as much knowledge about her disease as possible. Both reactions felt realistic (see, there's a theme here!). Mia's mother really bothered me, to be honest, because she's so obsessed with her daughter being popular and having an outwardly perfect life and this just feels yucky to me (note my aforementioned discomfort with the notion of popularity), but at the same time, it also seemed "real." 
 Anyway... I do wish that the friendships in SMaS had been explored more. Or maybe not more, but perhaps in a way that I ended up being more sympathetic to Mia's circle of popular circle friends. In the end, I still was uncomfortable with them, as much as I'd grown to like and care about Mia. (view spoiler)[There was also a scene late in the book in which Mia's cat dies--she has to have him put to sleep--and it's very, very sad, but in the back of my mind, I felt slightly manipulated. I imagine this is more of a "Sarah Problem" than it would be for anyone else, but I am sensitive about using animal death as a metaphor or to propel a plot forward--it's a thing with me. I ended up in tears, but it was more because I don't handle that particular element well ever, than because of the actual book. Does that make sense? (hide spoiler)] 
 Well, I meant to write a quick reaction to this so I could jog my memory when I write my "real" review, but this got a bit rambling. Definitely a recommended read--if you avoid cancer/illness books, SMaS may be one to check out anyway, as it's different and very, very well-done. The payoff for all the characters is hard-earned, and not just because of Mia's illness, and I LOVED that.