You want to make them in a crockpot? Or just keep them hot in a crockpot? I like this recipe from kraft.com but you have to bake them in advance. (Or I guess you could just make them in the crockpot but I've never done it.) They don't have a ton of ingredients so they're fairly easy and quick to make.
1 pkg. (6 oz.) chicken flavor stuffing mix
2 lb. ground beef (I like to mix 1 lb 73% and 1 lb 90% ground beef)
1/3 cup grated parmesan cheese
Bake 20 minutes at 400 degrees
Sauce:
10oz jar Concord Grape Jelly
12oz bottle Heinz 57
Making the sauce: Melt the 2 together over medium heat until the grape jelly is liquified. Pour over the meatballs and enjoy!