I cook beans in a pressure cooker. It's the only thing I use a pressure cooker for. Soak beans for 8 hours. Rinse them, cover with 2" water, add a tablespoon or so of olive oil and anything else you might want (like chili powder, for instance), then set the pressure cooker for 10 pounds pressure, let it build pressure (takes a few minutes till the top weight starts to jiggle), then turn down the heat and cook for 8 minutes. Turn off heat, and let the cooker cool down on its own (that takes an hour or so, but you don't have to stick around to watch it).
I like this method because I can do the active part of cooking in about 12 minutes. I don't really have a lot of time to hang out in the kitchen watching stuff cook, but I can pretty easily cook a pot of beans while doing some other 15-minute job in the kitchen.
I cook a whole pound of beans at a time, and it makes enough for almost a week for several people. This approach works for most normal beans. Roman beans and lentils are different, so don't use those with this cooking method.