I use a crate when I'm not home. But when I'm home I use a (or at least what I've been lead to believe is a) Buddhist monk method of keeping them on a leash on your belt.
A crate is good for teaching them bladder and bowel control but it does nothing to teach them the limits on the rest of the house.
I'm not big on crates for when you're home because it removes them from the pack. (I'm a pack trainer, not like the Dog Whisperer who claims to be a pack trainer but is actually more Pavlovian.)
I also hang a bell by the door and teach them to ring when they want to go out. (But be warned, as my niece found out, they ring to go out and play too.)
Petroleum based knitter, removing that nasty oil from the ground one skein at a time.