Ok, so not very therapy orientated, but I'm not just a therapist!
rugby. I think it might be good for tennis players and other racket sports too.
I have another drill I picked up from a tennis website that uses two cones around which you shuffle in a figure of eight. With this drill you always face forwards so you have to use small side-steps as well as forward and backward movements.
I sometimes do it using the tramlines as a guide during a warm up routine. This rugby drill could be done using the baseline and service line. Although I might adapt it if I thought running backwards on a hard court was dangerous!