For People who like Ally Carter's series Gallagher Girls and Heist Society:
1. Magic Knight Rayearth: I would say it's similar to the Gallagher Girls series because it's about a group of girls who have vastly different personalities but are still close friends who considers each other to be sisters and work well together. The girls in both series are also pretty good at fighting their enemies.
2. Kami Kaze Katiuo Jeane: It's similar to Heist Society because it's about a young girl that steals priceless art in order to help people although the reasons in the two series are very different.
3. Shugo Chara: It's similar to Ally Carter's series because it has a strong female lead who forms close and important friendships and has just enough swoon worthy romance.
4. Sailor Moon:Another series about a group of girls that are good friends and are capable of fighting evil.
5. Percy Jackson and the Olympians/Heroes of Olympus: I find that these series are similar to Ally Carters because friendship is an important part of the series.
6. Secret Circle: Has lots to do with friendships.
7. Rosario+ Vampire: It's set at a bordering school, the girls can kick some ass and friendship is an important part of the series.
For people who like The Hunger Games:
1. Battle Royale: Has a similar idea with having a bunch of kids kill each other on tv except this time they all actually no each other.
2. Uglies: Is another teen dystopian with a corrupt government that likes to control it's people.
3. 1984: A classic dystopian that tries to make thinking differently a crime.