Here is my crock pot Roast experience. I have tried several ways to make them and doing it this way creates the most tender, fall-apart pot roast you have ever had. You can buy any cut of meat too- even the cheap chuck roast and it will tenderize cooking it this way. I don't exactly have a recipe for it, but here's the method.
First, take about 1/4 C flour and season it- I used about 2 teaspoons garlic salt and 1 teaspoon pepper. Mix it together and then rub it on the roast. I sauted 2 cloves of garlic in about 3 Tablespoons of oil. Then you fry the roast on each side for about 4-5 minutes until its nice and brown.
Quarter one large onion and place the quarters in the bottom of your crockpot. After you brown the roast, place it on top of the onions. Add about 1 cup of water. I also put about 8 carrots and 3 chopped potatoes on the top. Cut them into larger pieces so they talk longer to cook. Sprinkle salt and pepper to taste over the top of the roast and cook on low for 8-10 hours.