This is the link to the New York State Military Museum Civil War information.
The museum is part of the New York State Division of Military and Naval Affair and is located in Albany, NY.
This is a great website resource for NYS regimental information. It includes some individual soldier biography and a few pictures. For instance:
The 121st regiment was known as the Otsego Herkimer Regiment. It recruited soldiers from Herkimer towns of
Co A: Manheim, Little Falls, Salisbury, and Danube
Co B: Winfield, Plainfield, Litchfield, German Flats, Columbia and Stark
Co C: Fairfield, Russia, Herkimer and Newport
Co D: Frankfort, Warren, Manhei, Schuyler, Columbia and Salisbury
there are also companies E, F, G, H, and I
The section on the 121st Infantry includes pictures of Corporal Edmund H. Yeoman, Brigadier General Delevan Bates, 1st Lt. Ulysses F. Doubleday and Sgt. Horation Gould Whitford.
This just barely scratches the surface of what is available on this website - take a look, you have to do a little searching, but it is worth it.