I found this Grout paint/finisher/sealer stuff on QVC.com and tried it last weekend. It worked great! All we had to do is "paint" over the existing grout (it was in good condition, just discolored) with the littler roller-top bottle, let it dry, and then clear off the excess "paint." It was really cheap too! I think it was like $18 or $20 a bottle. We ordered two bottles (one color for the floor and one color for the tiles on the walls) and only used about half of each bottle. Just wanted to share!