I just put a bunch of my 19th century baseball photos online at Flickr. There's about 180 photos that I've gotten from various places on the interweb, including American Memory, the Rucker Archive, and the Spalding Collection. Most of the photos that I uploaded are St. Louis related and some I've already posted here at TGOG. I'm hoping to go through the rest of my photos and upload more over time.
You can find my 19th century baseball photo collection here.