At what age do you think is acceptable to leave your child at home by himself/herself? Or is there an age? What do you think?

I don't think there is any particular age. It would depend on the maturity and demonstrated responsibility of the 'child'. It would also depend on whether you are next door or vacationing in Cancun. It would also make a big difference if the house is filled with loaded assault rifles, etc. My guess for a general rule would be 35 or 40.

I have to go along with Frank, It depends on the child, their maturity, and how long the parents are going to be gone. I do think Frank's given age is a little severe, however.

The National Society for the Prevention of Cruelty to Children (NSPCC) advises that no child should be left alone under the age of twelve, or overnight under the age of sixteen.
They say although most eight to thirteen year old are happy to be left alone for short periods, they are unable to cope in an emergency.
http://hcd2.bupa.co.uk/fact_sheets/html/leaving_children.html

My son was eleven when he would arrive home from school for a couple hours before I got off of work. I always checked on him as soon as he got in the door, made sure he had my phone number, told him the rules, and prayed he didn't break them. He did very well, was not any trouble to me. I think it does have to do with maturity, and you know whether they can be trusted or not.

PS: I also let my neighbor know he was there, just in case of an emergency, that way they kept an eye on him, too.