For older kids there's the new "Countdown" by Deborah Wiles or "This Means War!" by Ellen Wittlinger, both set during the Cuban Missile Crisis:
If you feel safer reading about war in alternate universes, "Ender's Game" by Orson Scott Card was a big deal to me, I'm not sure if it still holds up for today's readers. Two new titles that may take over for Ender are Cory Doctorow's "Little Brother" (though the book lost me on some of the technology. Perhaps I am more like Pat Sajak than I care to admit.) Just finished "Catching Fire" by Suzanne Collins and am beside myself with worry for when I will get my hot hands on the even hotter "Mockingjay." (Reading tweets of the BEA Scholastic/Mockingjay party, they said that Suzanne reads Katniss with a Southern accent. I'm not sure I can get behind that just yet. I'm trying. Team Peeta, for the record.)
Everyone in the children's book community is in love with M.T. Anderson's Octavian Nothing books "The Pox Party" and "The Kingdom on the Waves" as well as Laurie Halse Anderson's "Chains" (follow-up "Forge" comes out in October.)
Walter Dean Myers's has set his stories in the Civil War, Vietnam, and Iraq: "Riot," "Sunrise Over Fallujah," and "Fallen Angels."
And don't forget some incredible graphic novels: the online "Zahra's Paradise," "Refresh, Refresh," and "The Photographer."