I've been a big fan of John Ringo since I first read his book
Ghost. It's not one of his best, but it's action packed and the following books in the series are really good as well.
His two best series imo are the Empire of Man series co-written with David Weber, and the newest
Live free or Die set of books. Though I say those two are the best his other series are very good as well.
You can get all except the Live Free or Die series from BaenCD at
http://baencd.thefifthimperium.com/1...wsThatCatchCD/