My son wrote on his furniture using some kind of permanent marker. It was there for a long time. I took some GoJo Pumice Hand Cleaner and a paper towel and got all of it off!! It actually came off pretty easily. See before and after photos below.
His furniture is a popular kids furniture that is pine stained light cinnamon but not varnished. The pumice GoJo is a little bit gritty. If you need to try it on varnished wood, test in a hidden area. They make a creme version without the pumice. I have not tried that.
The great thing about this is there is no water involved. Gojo cleans without water. I rubbed it on, let it sit for a minute or two, then rubbed it off. I was blown away.
GoJo also took out red crayon from an entire load of laundry that was both washed and dried with culprit crayon. It took some time to rub it onto each red spot on every piece of clothing, but was well worth it.
Click here to check out their line of products and find out where to buy it. GoJo Pumice Hand Cleaner I bought this at Meijer in the automotive department and it was less than $4 for a large container. Wal-Mart typically carries it. You might also try Auto Zone or other similar stores.