JeffG is right about a tarsal gland and Tink's 69 (although dunking it is a bit overboard, IMHO. I always cut the tarsal glands out of does I kill, and put 'em in a plastic bag in the freezer. Before the rut, I thaw them and use them as is as a "comfort" scent.
I've only had estrous scent work for me once before, and it only brought in a non-shooter. This year, I bought some Tink's #69 gel, with some skepticism. During the rut (in MD), I put two drops of that gel on a tarsal gland, and set it about 3 feet off the ground in the crook of a small tree about ten yards from my tree. A couple of hours later, a nice six point came straight up the hill, sniffing. I put a Muzzy 125 through him at 7 yards, and he fell over about 30 yards away. I stayed put so as not to disturb a nearby buddy's hunt. That was at 4 in the afternoon.
Twelve minutes later, I heard some stompin' and snortin', and out of a thicket comes a nine pointer that made my eyes bug out. I guess he caught wind of the doe pee AND the six pointer, and didn't like the competition. Shot him at 8 yards. Tagged out in twelve minutes (had already taken more than the two does required to shoot a second buck in my county)! I'm a believer in scent, now.