Just found a nice collection of early photographs of London life, including quite a lot images from the river. It's part of an exhibition at the Tower Bridge called "London in Black and White" and you can see a nice selection of them on the Telegraph web site here.
The caption for the picture above is as follows: A flat-bottomed barge or "lighter" going downstream towards Southwark Bridge, circa 1905. These barges, moved along by long oars, were a common sight in London until as late as the 1960"