Slow cookers are especially good for cooking tough cuts of meat.
Most vegetables don't need the slow cooking as far as I know, although almost any vegetable stew would do nicely.
My standard recipe is to chuck in some onions and a tin of tomatoes and any vegetables too slow to get out of the way. Plus lots of L&P sauce.
A slow cooker would be good for raw beans such as kidney beans, but given the risk of poisoning if they aren't fully cooked I always use tins. Pulses work well, as well, if your system can take them.