M.D.
My 4, 6, and 8 year old have had chorse since they were born...we have always taught them to pick up after themselves...doesn't work so well some days :).
We rotate weekly with vacuuming the living room, bringing the dirty clothes to the laundry, and wiping the table and counters after meals. These are easy things that all need done either daily or every other day.
They also help with unloading the dishwasher, loading their own dishes, changing and taking out the trash, putting their pajamas/underwear/socks away, my dauther loves to mop, the all like to dust the stairs, hanging up their own coats and keeping their shoes out of sight, etc.
I'm with some of the others in saying that we are a family and it takes all of us to have things running smoothly. If we don't all pitch in, the house becomes a mess. Like it is now :).