Now that you have read and apparently enjoyed Starship Troopers, I thought it might interest you to know that it is only the beginning. When Robert Heinlein invented powered-infantry armor and dropped soldiers in pods from spaceships, he also helped create a new subgenre called military science fiction.
If you liked the idea of soldiers in heavy battle-suits that give them near superhuman abilities, I would suggest you check out John Steakly\'s Armor, in which a young man hides from his own past inside a suite of armor, and when the stress of battle takes over, he hides even deeper in an alternate personality known as \'the engine\'. Of course, these “armors” are the only things keeping him alive as a computer glitch sends him into combat again and again on the horrific planet called Banshee.
If, however, you prefer a more traditional take on armor, you might enjoy David Drake\'s Hammer\'s Slammers. The Slammers are a mercenary organization that travel from planet to planet selling the services of their nuclear powered hover-tanks to the highest bidder. David Drake, a Vietnam veteran, has written a host of short stories and novels about the group, and they tend to be harsh, brutal, and as grittily-realistic as science-fiction can be.
Then again, military science fiction doesn\'t have to be about mercenary killers or borderline psychotics. In fact, one of the most popular works in the genre stars a likable young boy named Ender Wiggins. Winner of both the Hugo and Nebula awards (two of science fiction\'s highest honors), Orson Scott Card\'s Ender\'s Game is about a military prodigy who is taken away from his home to train at a special military academy. It\'s a story about being a boy in extreme circumstances and about how things are not always as they first appear. There are few military fans who will have forgotten Ender\'s realization that in zero-gravity combat direction has little meaning, and the best way to assault a defended enemy point is feet-first, thus it is always best to remember, “the gate is down”.
These days, military science fiction, like most of science fiction and fantasy is dominated by series. The most successful of these is probably David Weber\'s Honor Harrington Series. However, for my own money, I like Dan Abnett\'s Gaunt\'s Ghosts. This series now spans eleven books and has been described as Richard Sharpe is space. This isn\'t terribly accurate however, as the Ghosts novels feature an ensemble cast, and, even on the field of Waterloo, Sharpe never saw the body count that is accumulated in some of these books. There are those who may argue against this series because it is based on a game (Games Workshops Warhammer 40,000) and that it has strong fantasy elements (they often fight demons), but if you like non-stop military sci-fi action, these books are some of the best.
I realize I\'ve probably overloaded you with books, but there is just one more work I would like to mention. Should you only ever read one more book of military science fiction, might I suggest Joe Haldeman\'s Forever War? The definitive work in the genre, in my opinion, the Forever War, combines incredible action sequences, clever twists, and the idea that faster-than-light-travel can mean that hundreds of years pass while soldiers go and return from distant battlefields. Thus, not only do we get a fast-paced story, but we also see an actual evolution of warfare over the career of one soldier. It is a monumental work of imagination and one not to be missed.