I also do it Jim's way, but I brown the roast first, covered with flour...
then I cover the whole roast with a layer of horseraddish (about one jar of Gold's), then put it in the crockpot...
The horseraddish adds flavor, but all the heat cooks out of it, if that is a concern...
I like to use a chuck roast... as long as you don't overcook it, it will remain very moist...
the drippings make a great gravy...