Easy, eco-friendly scrub-stuff! Using toothpaste and baking soda! However, word to the wise: I would think this would be very, very abrasive, so use it gently and consider a backup plan to refinish the surface afterward. And not that white boards are eco-friendly, but their tip to clean off permanent marker is a keeper, if it works.
And in line with our discussions here about spending and life, Get Rich Slowly has an interesting post compiling the “splurge” confessions of a bunch of personal finance writers. (I won’t be offended that he didn’t ask me.)