I found a new marker for dark woods the other day. I do welding as well as wood working, and I took a soap stone marker to some walnut... NICE!!!
I had been looking for a replacement to chalk since it seemed to embed in the pores of some woods and was difficult to clean out even with mineral spirits.
The soapstone seems to come off very easily. I'll let you know how it finishes over a cleaned off area later, unless someone else beats me to it.