J is 4 1/2. We have a magnetic responsibility chart that we use partly for behavioral stuff and partly for chores. We change it up every few weeks depending what needs attention. Sometimes it's a general "help mom" or "help dad" magnet. Things he has been taught to do using the chart are to clear his dishes, put dirty clothes in the basket, and clean up his toys. [These are regular things even when they're not on the chart.] He can't reach most of the places the dishes are kept, but he loves to put away the silverware and help me with laundry.
This is a good thread and one I'll be watching!