I'm a big reader here, so here comes my suggestions:
Anybody who likes Heinlein, Clancy, Flynn, etc should check out John Ringo. His first book, A Hymn before Battle got me hooked. It's an alternate timeline where Earth is contacted by aliens to help with a spreading menace, the Posleen. Then they invade the earth. He's also go a series called Through the Looking Glass, and the Kildar/Ghost series which is pretty hard core, but still good.
I'd also recommend John Birmingham. His trilogy starting with Weapons of Choice is about a Naval taskforce that gets transported back to the battle of Midway, a la the Final Countdown. Pretty good stuff about not only the affect of modern technology on the past but on modern sensibilities.
Finally, I'm a Star Wars geek, so the Republic Commando series by Karen Traviss. It is a little more hard core than you'd expect with Star Wars and has one of my favorite characters, Kal Skirata, a Mandolorian (Boba Fett armor is Mandalorian) who trained the commando squads. Very good read for four books.
I REALLY recommend the John Ringo series, A Hymn Before Battle, Gust Front, When the Devil Dances, and Hell's Faire. That's the order of the books. There's other set in that universe, but these are the main ones. I went through the first three in 4 days (had to work part of the time
Almost forgot. Ringo did a book called the Last Centurion that I think everybody here would appreciate. It's part fiction and part political statement, but let's just say he's not big fan of liberals/democrats.
Check out his website at: http://www.johnringo.com/Home/tabid/1574/Default.aspx
He's also done some great op-ed pieces guaranteed to put a smile on your face.