What do you know about grout color sealer? Well if you have tile you should really consider getting to know it because this stuff ROCKS! I don't get too excited about commercial products. If you don't need special training and a letter from Congress to order something, I generally tend to think of it as weak.
This product has definitely changed that line of thinking. It's called NA 6700 Grout Rescue (which still sounds kind of contraband-ish). It's recommended for really dirty grout lines, but I was using it to match the old grout with the new tile work in the kitchen. For $10, I didn't pay much attention to the direction on the bottle, just sort of wiped it on till I got a good match.