This is actually the recipe that came with my Crockpot, but I've tweaked it a little.
2 or 3 potatoes, sliced (or diced or cubed or whatever)
2 or 3 carrots, sliced
1 onion, sliced
1 beef roast
1/2 cup beef broth (or water)
salt, pepper, and garlic powder to taste
2 or 3 dashes Worcestershire sauce
Put potatoes, carrots, and onion in bottom of the crock pot. Add beef roast (fat side up, if there is one). Pour in beef broth or water. Add salt, pepper, and garlic powder to taste (I just eyeball this). Add Worcestershire sauce (again, use what makes you happy...I put in about 3 "dashes"). Cook on low for 10 to 12 hours.