My friend has 10 of them which are pets but she shows them as well. She loves them, says there great with her kids. They do smell though and they live out side in hutches with runs which must be escape proof. You can walk them with a ferret harness : ) If you get a girl ferret you must have them neutered as if they don't get pregnant they die! I think the boys are more smelly though.
I used to have ferrets. I had special 'ferret clothes' I used to wear everytime I handled them, as they smell SO bad. Literally, you just have to pick one up for a minute and your clothes will smell for hours.
Females must be neutered as spugs has said.
They are absolutely adorable, great fun, and really naughty. Mine used to have an outside run about 8ft by 6ft.
They are very easy to house train. Ours went through a stage of escaping their cage and coming to knock on the back door to come and play.
They eat dried food, but love the occasional dead rabbit thrown in.