Zubrin proposed such a system...
but I think that's one of the weakest parts of his design. You're introducing a lot of new failure modes (such as the winches not working properly or the tether breaking) as well as a great deal of complexity for things like course correct maneuvers. I also wonder if there might be some dampening issues for oscillations caused by people moving around.
A fast trip in a small vehicle, perhaps with a centrifuge to reduce muscle atrophy, is a better idea, IMO. We don't want the crew to have to spend weeks adapting to Mars' gravity after they arrive. While they don't necessarily have to be able to "hit the ground running", they'll only have a limited time on the surface and we'll want to make the most of it.