I used to work for a company that manufactured cheerleading uniforms. The tops were knit and the knitting machines would often leave black grease on the fabric. We used this spray to get the grease out. It's Sullivan's Fast Spot Remover. You spray it on the spot, wait for it to dry, then launder. I usually get it at my local Hancock's Fabrics.
eta: I wonder if they've discontinued it! I just tried to find a picture of the can online and can't locate one. What a bummer, I'll be so disappointed if it's no longer available!!
