The Civil War Preservation trust has a lot of incredible resources for helping teachers cover the Civil War. This includes iPad, iPhone, and Android apps for each major battle, an entire curriculum for elementary, middle, and high school, and a ton of other resources for teachers.
To me however, the best resource they have created is this animated map and video of Antietam. Created in honor of the battle's 150th anniversary, it does an amazing job of showing how the death toll mounted so quickly and terribly. The flash video mixes in reenactments and video footage with the animated troop movements on computer-generated maps for a truly amazing multimedia experience. This is exactly the type of media that Students of History supports - it uses technology effectively to support learning, makes the content relevant and engaging, and is effective for all learners.
Definitely recommend you check this out when you cover the Battle of Antietam in your classes!