We have 1 acre and this is what we have:
Divided the acre into two (would prefer it into 3 really to allow better rotation)
We have Ouessant sheep. We bought 2 and are breeding from them - now have 6. They are small and as someone else said you can have up to 10 on an acre - I think without grass we could sustain around 12 easily during spring and summer, but we have to give them hay in the Winter. We are currently breeding enough to up our numbers and once have got enough we will sell the lambs. Pedigree ouessant ewe lambs cost around £300, so there's a possibility of a profit, but obviously you need a market for them and we haven't tested that yet. We will put any unwanted lambs in the freezer. We don't have enough land for our own ram though so we have to factor in the cost of using a stud service. And you need transport.
We have planted 30 fruit trees in about 1/3 of the acre - apples, pears, plums and cherries - should give us plenty of fruit!!! We did this mainly for conservation/aesthetic reasons, but it has left us with a bit of a problem of not being able to graze it as the sheep eat the bark.... But I do love our new orchard!
We have 12 hens free ranging in the orchard - sell the eggs to neighbours.
We have a large vegetable plot, which sustains our family from now until about November and provides a few bits and pieces over the winter. We plan to erect a poly tunnel and large fruit cage with time.
I have thought about pigs and might try them in the future, but would buy them as youngsters to fatten over a few months and then slaughter, rather than having them on the plot full time.
I love our little patch of land - it provides a bit of food for our family, but most of all it provides a lifestyle, exercise, education and fresh air for us all, including my two small children. That is the reason we do it. We have spent a small fortune on it so far with all the fencing and whatnot. We certainly don't ever expect to make any money from it, but it has far great value to us in term of quality of life.
The book "Living on One Acre Or Less" by Sally Morgan is brilliant!