When I had my cats, and they were in good health, they both went outside for at least 6 hours a day, when they felt like it. I think it's important for cats to get out and about and explore surroundings and my cats benefitted from it. A cat on a leash is a bizarre idea to me, I have heard of it before but I just don't get it. My cats had a much more fun life rather than being stuck indoors their whole life, but I'm not going down that line of indoor and outdoor cats. Of course, I can understand if a person lives on a particularly busy road or if there are dangerous stray dogs about, and of course they MUST be fixed, but I have heard excuses of 'I'm worried Kitty will get scared' or 'Kitty might forget where the house is'. Cats are intelligent and sometimes I feel people don't give them enough credit for their ability to be independant.
Sorry off track just had to add in..

I believe people that live in the city should keep their cats INDOORS or have them on a leash or train them to stay in their OWN yard.
Loose city cats cause problems. Period. Cats can be intelligent - ie. training them to stay on their own property. Some cats do lack the idea of getting OUT of the way of a moving vehicle instead of running FOR it.

I agree with loose country cats though. They keep the mouse population down in barns - although males tend to mark the horses hay(annoying problem, hay is expensive now!) other then that, they prove useful in the country.