My kids are a little (just a bit) older then yours.

From the time they were interested, they would push the vacuum cleaner around for me (who cares if I had to do it again later).
They put their clothes away - and into the right drawers (something I'm particular about), they both know how to use the washing machine and dryer, hang the clothes on the line - not wonderfully, but if it gets dry, who cares. I will fold the clothes and put into the right persons pile, its their jobs to pack all the folding away. It's also their jobs to bring the washing in for me.
My eldest will cook a meal once a week - this is on top of working up to 6 nights a week, I figure he needs to learn at some point how to prepare and cook a meal - I then get him to clean up after himself and the rest of us. The youngest is just beginning to cook, although they have both been preparing vegetables for many years. DS2 will cook vegetables using the vegie steamer. They both take turns emptying the dishwasher and will refill it under sufferance.

My eldest has been doing the ironing for me for the last six years, DS2 starts learning after Christmas. They both have assigned cleaning jobs that we tackle each Sunday. A lot of this is because I work from home with long hours, so appreciate all the help I can get. Some of the jobs they do each Sunday, I will do as well thru the week. They also mow the yard for me. DS2 mows and gardens at his grandparents, which DS1 used to do before he started working.

In the start I gave them each pocket money for helping do jobs, but now pocket money is dependant on how much spare money I have at the time. The eldest doesn't get pocket money from us - he works so gets paid there - but I do buy him DVD's/games/music occasionally.

I think it also teaches them responsibility as well as contributing to the household.