I grew up reading science fiction, starting with Tom Swift, progressing to Edgar Rice Burroughs, and finally Robert Heinlein.
A while ago, a friend hooked me up with a book that I devoured in one sitting, between 8 p.m. and 2 a.m. (on a work night, no less!).
The book was "Old Man's War," by John Scalzi, and it feels very much like a Heinlein novel. I enjoyed it more than I've enjoyed any book in quite a few years. I have since introduced five other people to it, and all have raved over it.
The ... well sequel is the easiest word, but not exactly accurate ... second book set in the same universe has just come out, "The Ghost Brigades." I bought the first copy from a local Barnes & Noble, and repeated the at-one-sitting performance; I highly recommend it as well.