Some of our good friends do it with chips. They got those laminate chips from the kitchen section of the hardware store (with permission, of course), and have a little system where they get chips for completing chores or time with whatever they have to do to earn media time. Each chip is worth 15 min media time. They also have to use up a chip if they watch with a sibling..you're in front of the media, you give up a chip
I'd definitely chart for time reading, etc...good time to discuss different kinds of charts and do a different sample for each child - bar graph, data graph, data table, etc.