If your kids are like mine (well, mine and our daycare kids), and allowed to watch a very limited amount of television, they will probably be desperately excited when it is on - and perhaps even cluster around the screen, to get as close as possible (because you don't want to miss a moment of the Bananas in Pyjamas!). After repeated efforts at "stay back from the TV - further, further...", I knew I needed another plan.
I now set up a picnic blanket on the lounge floor, as far away from the TV as I want the kids to be. They are not allowed to go past its front edge. This is a clearly marked line, and there can be no arguments about creeping closer to the TV. My real tip is to make it a comfortable, fun place to be -- add some cushions, have their water bottles close by, and maybe even a snack, if it is the right time of day. Make sure to allow some room around behind the blanket, for dancing etc, and for those kids that lose interest in the program. Pretty soon your kids will WANT to be on the blanket (and therefore away from the screen). They can all see, there is room to stretch out and it is almost like having an inside picnic, at a regularly scheduled time!
For more great tips, go over to Rocks in My Dryer.