[LeoPanthera]

This works because the solvent base for the ink is alcohol, so a much simpler method that doesn't waste ink is to use a small spray bottle of isopropyl alcohol. Ideally 99/100%, if you can get it. (Try eBay.)

This doubles up as an effective whiteboard cleaner.

[lathiat]

Hand sanitiser is great for this. A dab of whisky on a paper towel also works well.

[firefax]

Yeah, I'm mostly posting this for folks who might not have access to ISO, but if you do, that is the best solution.