I just finished reading the new book in the Enderverse, where they are doing the first Formic war and Mazer Rackham is introduced. It was awesome!! It kept right with the Marvel comic release of the book with the same title. Highly recommended!
I read The Forever War a while ago and liked it =)
I haven't read any of the Warhammer or Halo books. I used to play the Warhammer 40k miniature game and liked it. I have never been a fan of fps games though, so I haven't tried any of the Halo books yet. I will pick one up and give it a try!
I have read every book in the Ender series and loved them! I had never heard of Caves of Steel until now. Wow that is an old book!
Those are some really good suggestions! Keep them coming! =D