Richard,
Do a quick web search for Red Wine Venison Marinade. I don't remember which one I used exactly, but I have done a few venison racks with this and it is really good. The basics of it are red wine, vinegar, olive oil, crushed garlic, fresh herbs and fresh cracked pepper. IMO,it should stay in marinade for at least 24 hours to really make an impact.
Opps, I just saw this was a slightly old post, but maybe still good info for someone.