i stumbled on these by accident. They are not waterproof, but they do keep the toes warm (down to about 35 degrees so far for me). I found them a little difficult to install the first time, but subsequent installs are fine. On wet days, they get a little dirty, but they clean up fine in the wash with the rest of the gear. My only worry is, over time, that the heel may wear through if you walk on them much. They aren't terribly expensive as shoe covers go, so definitely worth a try.
Edit: I wear these over Pearl Izumi Road III shoes. They have a velcro strap across the toe and a single BOA on the tongue. Some care has to be taken when putting them on over the straps and knobs, but it's not too bad.