You can feed Foopets, breed Foopets, wash foopets, play with Foopets, even design a room for your Foopet!
You choose a breed of cat or dog, name it, and then you buy food, toys, and items to design it's room with money you earn from games, or real money which you can use to buy FooDollars. Or there's the option of buying from other members.
there are also forums to advertise or just chat!
You can buy several Foopets, and Breed them when they're old enough.
I personally find Foopets not to my liking. I have quit because I was charged thirty dollars (Of real money) for a pixel! A virtual pet is not worth that. Not only that, but they took it away, and will not refund me money, or give back the pet.