Percy Jackson and the Olympians is a 5 volume series (complete) and the first book was recently made into a movie. I don't like to get into spoilers, I think you can glean most of this from the back of the first book. In fact I think the summary on amazon may be more spoiler-y xD;; but I'll cut this just incase.
The star of the series Percy Jackson is a 13 year old boy that has been kicked out of every school he has ever been in. Percy is dyslexic, has ADHD and trouble always seems to find him. At his new school he makes a friend named Grover whom he protects from bullies and is the favorite of a history teacher that expects more out of him despite his obstacles which frustrates him. And then his math teacher tries to kill him.
Percy learns that not only do mythical monsters exist but they want to kill him and kids like him. Kids like him? That's right because Percy's absentee father turns out to be one of the Greek gods, making him a half-blood (half mortal half god). The gods are still very much real and still having flings with mortals. The only safe place for their offspring is Camp Half-blood which is sort of a Hogwarts-like setting on a much smaller scale. They just have to stay alive long enough to make it to that protected area.
The kids are in a constant battle for survival so they have to be trained to fight. Instead of classes in magical self-defense they learn to fight with sword and shield, instead of being sorted into houses they are put into cabins based on who their immortal parent is. The Athena kids are smart, the offspring of Hermes are prank-loving thieves while the children of Ares are pretty much bullies. They have violent chariot races and capture the flag competitions. However Percy doesn't get to spend a whole lot of time at camp before he takes up a quest with Grover and another camper to prevent a war between Zeus and Poseidon.
Why I like this series:
The use of greek mythology (the gods, medusa etc). It never over explains everything so it doesn't feel like you're getting a history lesson. It's fun when you can recognize certain monsters or settings but if your knowledge is rusty you can still enjoy it without needing to look anything up. The plot doesn't drag, there is lots of action but also a little romance that doesn't feel forced *coughHARRYGINNYcough* because it develops more realistically (I actually like the het pairing though I do have a slash one too). The gods have interesting personalities and have modernized to some degree and the characters have real plausible motivations for what they do, you will probably change your mind about several of them before it's done. There is closure of the plot but it's not the "and everyone lived happily ever after" kind. They still have problems like surviving outside of camp that isn't going to go away just because someone saved the day.
Harry Potter fans, if you liked the whole house sorting thing you will probably like the cabins idea. Like Harry, Percy has talents that he never knew he possessed and must learn how to use them in order to save himself and his friends. There is a big bad guy like Voldemort but he is far more manipulative and doesn't go out lame like him. There are probably a few more similarities but you'll just have to read to find out. Personally I think Percy Jackson and the Olympians gets more things right. LOL I swear I liked Harry Potter, I just think it didn't quite live up to its potential.
Greek mythology fans, expect the myths to be a bit toned down. What I mean is that they don't mention that satyrs are super horny (lol I made a funny) and mermaids are made out to be mischievous maidens instead of ones that drown people. However the author makes most of the non-human characters like centaurs, nyaids (tree nymphs) and water nymphs interesting and even some of the bad ones have depth.
You don't even need to go to the library.
Here is a zip file of .pdfs for all 5 volumes :D And now I don't know what else to say except read it! Please? I need more people to spazz with me. Also let me know if I did a good job XD my persuasive skills are a bit rusty.