Token economy systems for independence

A simple token economy system has been part of my parenting toolkit for a long time. For my guy,  I've usually implemented this using a small laminated sheet with a series of boxes to fill in or place checkmarks in, and an erasable marker (not dry-erase). Don't have a laminator? See my blog post about useful materials for home-based learning and programs. I target a behaviour (being quiet for x minutes, trying something new, sitting for x minutes, whatever) and then award checkmarks (or filled-in boxes) to my son, with a defined reward (a break, a treat, a favoured activity) when all the spaces have been filled. What I love about these systems is their flexibility (you can arbitrarily give extra marks where necessary to make the experience positive), their clarity and their portability.     

As the years have passed, I've turned to such systems less and less often, finding more natural reinforcements and recognizing my son's maturity and growing flexibility that doesn't require such tools. However, I decided to dust off the old approach when faced with the challenge of encouraging independence. Yes, he does lots of household chores, and is better at following time-based schedules (perhaps he's a little too time-focused: this is a kid who when reminded that he needs to be upstairs at 9:30 will respond "it's 9:29!" - his watch obsession might be a topic for another post), but unprompted daily activities are still not as common as I'd like. So I came up with this, which rewards checkmarks not for doing something, but for doing something without being prompted:

So far it seems to be helping, although I've had to be rather liberal about what the "something" he is doing unprompted might be. Have other practical ideas for promoting independence? I'd love to hear about them.