I Love Sci-fi / Fantasy!
I just read what everyone else offered up & there are some true gems in their suggestions. Enders Game is a definate must. As a matter of fact I would suggest you immediately drop whatever you are reading now & go & get it & see what it feels like to be truly entertained! Then read Sir Apropos of Nothing by Peter David, & be transported once more by genius story telling. Paula Volskey is also someone I highly endorse. Half.com probably has all the books everyone mentioned & you pay a fraction of the cost. I really hope you enjoy these books!