Thanks for the compliments everyone. /forums/images/graemlins/smile.gif
Yes, the floor is sloped toward the drain. I didn't build the garage, but I know the person who did (before we bought the place). He basically put the drain in the middle of the floor and an inch or two lower than the outside edges of the floor pad. The floor slopes all the way from the edges to the drain, so there isn't anyplace that water will stand in the garage.
There is a standard PVC drain with trap (about 3" pipe I think) which simply goes under the floor and exits a few feet outside the garage. The ground is slightly sloped on that side, so the drain pipe can be sloped slightly downward the entire way and still exit above ground. Any water entering the drain exits outside and flows across the "yard" and into the ditch.
The biggest problem is freezing in the winter - basically the drain is non functional, but I don't actually use it much anyway, even in summer.