Given that I'm just not getting out with the camera at the moment, the next best thing is reading and looking at images in order to try and keep learning.
Tim Clinch, writing in the latest 'Black & White Photography', talks about the impact seeing Dorothea Lange's 'Migrant Mother' for the first time had upon him - a 15 year-old at the time. He provides a couple of good links. This one documents Lange's own recollection of capturing the image and this one gives more information about the subject, Florence Owens Thomson.
I suppose these are only of interest if, like Clinch (and me), you agree that it is one of the truly great images in photography.