Excellent replies already above!
Here's one more -- in my humble opinion the best one-volume history of the Second Afghan War, compact but thorough: "The Road to Kabul - the Second Afghan War 1878-1880," by Brian Robson, originally published in 1986, as seen here on Amazon:http://www.amazon.com/The-Road-Kabul-Second-Afghan/dp/1862274169
Also, just in case you're not yet aware of it, here's a link to Garen Ewing's fantastic Second Afghan War history site, which is a fantastic overall resource:http://www.garenewing.co.uk/angloafghanwar/
Of particular value for us wargamers is the "regiments" page, which lists every British and Indian regiment which served in the war, along with any battle honours they earned during the campaign. Here's another link directly to that page:http://www.garenewing.co.uk/angloafghanwar/waroffice/regiments.php
Last and also least, here's a link to my own humble blog, which features a lot of Second Afghan War model terrain, miniature armies, and historically-based scenarios:http://maiwandday.blogspot.com