HawkSong Series! The first book is awesome, it gets a little confusing at the end. (BTW Does contain a pair of lesbians in the series. But that's near the end. And it's for good reason.) RATED: T for violence and Suggestive Themes
Song of The Lioness Series by Tamora Pierce: Medival Times:Twins, a boy and a girl, are complete opposites. Boys usually go and train to become knights, while girls go to a Covent and learn magic and ettiquet. Turns out, the twins want to do the exact opposite of what they're required. Alanna wants to become a knight (which is illegal and punishable by death) and her brother (forgot his name) wants to become a sorcerer (which is legal.) So you pretty much read about Alanna's life. The twins both have a special power called the GIFT. Which is very similar to Eragon magic, except they don't have to speak words most of the time. RATED: T for violence and reference to suggestive themes.
My Side of the Mountain: Rated E: Very adventorous and interesting. Boy runs away from home to live off of the mountain.
The Immortals by Tamora Pierce: My younger sister is reading them and she really seems to like them.
Lord of the Rings: Seems like a popular choice.
Tell us the books you've read, so we have a better idea on what you like.