Most of us have one, kicking around in a cupboard or collecting dust on a shelf. Well go dust it off, it's time to start using it.
I got mine as a present from my mom a few years back, and at first I thought "Great, another thing to take up space." It's nothing fancy, a Bravetti 4 quart cooker with three heat settings and a removable stoneware dish. It sat around for a while, and then one day I fished it out and tried to figure out what to do with it.
A slow cooker (or crock pot to some) does as the name suggests, it cooks slowly. While fancier models have digital temperature settings and probes and such, mine has a 'low' and 'high' setting, as well as 'keep warm'. Ultimately, on models such as mine, both low and high settings will bring the food to the same temperature, the difference is simply in how long it takes to get to it.
Do a Google search for slow cooker recipes and you'll get a bazillion and one results. A good place to start is Stephanie O'Dea's A Year of Slow Cooking. She undertook the challenge to cook something in her slow cooker every day for one year. And it's not just soups and stews (though there are plenty of those)... she came up with some very interesting things to do with her slow cooker. She outlines the recipes and how they turned out. The Kitchn (no that's not a typo) also has a number of recipes and info on slow cookers. They walk you through the basics of what a slow cooker is and how to use it which can help you make use of yours more effectively. Tipnut also has quite a bit of info on slow cookers.
The majority of recipes you're likely to find will be stews and roasts and the like. Since it is designed to cook long and slow, it lends itself to tougher cuts of meat and root vegetables that take time to soften up. Of course, you can do that in an oven or on a stove top as well... so why bother? Well, the main benefit of a slow cooker is the "set it and forget it" aspect. You can set it up, turn it on and more or less let it do it's thing for hours on end. While I've let my slow cooker do it's thing over night, I would hardly feel comfortable doing that with the oven. It's probably not a good idea to leave the house with it on, I wouldn't worry too much about running to the store and leaving it on, while I'd never dare to do that if I had something on the stove.
Beyond the requisite stews, you can do quite a bit more with a slow cooker. I use mine every Sunday to cook a large batch of steel-cut oatmeal that I then portion out and reheat in the morning for breakfast. Using a 1 to 4(ish) ratio of grains to water, throw in some cinnamon stick and a bit of salt, set it on low and in a few hours I have perfectly cooked oatmeal. Quite a treat on cold winter mornings, and leaves plenty of room for additions like dried fruit, etc.
You can also do things like cooking dried beans, making fruit butter, making yogurt and even making candles with a slow cooker. And my favorite around the holidays, making dulce de leche with only one ingredient... unopened cans of sweetened condensed milk. If you've not tried this particular recipe, you *must* give it a shot. It's a bit strange putting unopened cans on to cook, but hey no clean up after, and the results are simply lovely.
If you want to start out simple, a beef stew or chili recipe is usually a safe bet, assuming you're not vegetarian. If so, then aim for a root veg stew or maybe a soup instead. If dealing with meat, do yourself a favor and do a little research on cuts of meat... which ones suit themselves to being cooked by which method. Something like this will get you started. This helps you not only end up with tasty results, but also save a bit of money and headache at the grocery store. The 'less tender' (read: less appealing) cuts are often less expensive but can also be labeled with confusing names and information. Look for words like chuck, rump or round... those are the most worked muscles (shoulders and legs) which makes for a tough steak, but a delicious stew.
So, what are you waiting for! Go scrub your root vegetables and get crackin'! ;)