hmmm....i've read so many, but most are fairly popular, but here are some suggestions:

Dandelion Wine by Ray Bradbury (it's a little odd, but very good)
Ender's Game by Orson Scott Card (best sci-fi i've ever read, whole series is great, i could go on forever about this book.)
the Prey series by John Sandford, starts with Rules of Prey and goes on from there through about 12 other books
ok, only two more, both really good science fiction (not sci-fi). The first one is Sphere by Crichton (great book if you haven't already read it) and the other one is Gravity by Tess Geritsen (probably the best book i've read in a while). Enjoy!