For those posting Mexican recipes, I'd like to give a little advice (from a Mexican who makes a lot of food):
Cumin is not only your friend, it is ESSENTIAL. It's included in a lot of recipes already shared, but there's one thing that I have to stress that will change the way you use it. FRY IT.
Cumin, raw, tastes very earthy with a tiny warm pepper-like bite. When it is roasted or fried (in either powder or seed form) the flavor profile changes quite a bit. Smoother, nuttier, and more rich flavors rise to the top and it become much more rounded than just raw cumin. The key, however, is to make sure you don't burn it!
If you're going to make a slow cooker meal using cumin, here's my recommendation:
In a small sauce pan, heat some oil on medium high heat and then add your onions. When they're getting nice and soft and starting to brown up a bit, add your garlic if the recipe calls for it. Once it's started to get translucent, add your cumin and other spices. Turn down the heat just a bit and continuously stir. You're just looking to fry the spices a little bit, so maybe a minute (at most) of frying at this medium heat will be enough. Then add your water to the pot, or just use a spatula to scoop it all into your crock pot.
This step is often left out in a lot of recipes and it's so important!