There are several places where you can play draughts on-line ( in the real-time and by e-mail )
We put here just few links with the short description.
If you know more - please advise

Real-time


KNDB damserver
(100, Brazilian, 144)

PlayOK (Poland)
(100, Brazilian)

Microsoft Game Zone
(Checkers)

On site


AShShI (Russia)
Different

Ludoteka (Spain)
Different

E-dama
100

Play Arena
Different versions