A few not often seen unit studies that I don't believe have been posted yet:
19th Alabama Infantry, Spring 1862
They were in the Gladden-Deas Alabama Brigade in the AoT.
21st Ohio Volunteer Infantry, Corporal, Company C, September 1863
The 21st Ohio is widely known for its famous stand on Snodgrass Hill at Chickamauga. They were armed with Colt Model 1855 Revolving Rifles. The corporal also wears a Hardee Hat, which was typical of Federal troops in the Western theater.
Longstreet's Corps, September 1863
When Longstreet's Corps traveled west to reinforce the Army of Tennessee prior to Chickamauga, a large number of troops were wearing their recently issued uniforms of blue-gray English kersey wool. They caused some confusion along with a few friendly fire incidents at Chickamauga, as the uniforms were easily mistaken for the Federal blue.
2nd Connecticut Heavy Artillery, 1864
Obviously what looks like a depiction of the regiment at the Siege of Petersburg. The 2nd Connecticut Heavies were one of the heavy artillery regiments sent to the Army of the Potomac later in the war (May, 1864) to fight as infantry. They saw their first major action at Cold Harbor, where they lost heavily in a frontal attack on June 1. It was credited with temporarily breaking through the Confederate lines and capturing 300 prisoners. It later participated in the early stages of the Siege of Petersburg, the 1864 Shenandoah Campaign, the breakthrough at Petersburg in 1865, and the Appomattox Campaign.