I put a chunk of frozen hamburger meat (never cooked) in the crock pot with some water and taco seasoning and it thawed the meat and then cooked it.
It was not faster than cooking it on the stove, but it saved on the dinner-time rush.
2 lbs taco meat (frozen---but I think you could do fresh/thawed also)
1 1/2 C. water
2 packets taco seasoning
Place all ingredients in crock pot about lunch/nap time. Cook on high until dinner. Every few hours break up meat and stir. When ready to eat...drain fat and water.
Here is the blog post I googled and found the info on http://www.aroundmyfamilytable.com/2010/10/slow-cooker-taco-meat/
