Hogs of War, a blog by Gillers, is a great resource on all things A-10: flight simulations, news, books and other goodies. Hogs of War has referenced this blog a couple of times (thanks Gillers! :) ).
In Hogs of War's "Books & Reading" section, there are two great books listed. One is Smallwood's "Warthog: Flying the A-10 in the Gulf War". Excellent book. The other book is "A-10s Over Kosovo" which can be downloaded for free from the Air University Press website.
Keep up the good work Gillers!