A lot of great stuff in this thread.
Here's a couple. First is Dummy Taylor and Leon Ames at Giants spring training, 1906. Love that the snap has its own little mount:
Next is a group of snapshots of the Polo Grounds found in an album entirely from 1901. So these are quite early for the type of photos they are, and probably the earliest wide-shot, in-game photos I've seen of the Polo Grounds. For their small size, scanned large the images are surprisingly sharp and hold an incredible amount of detail:
A couple of them a bit larger. Note the ump behind the plate, and then behind the pitcher:
