I received some Memorex 'Metallic' Water Based CD/DVD Markers, and I must say that they are excellent compared to the regular water based Memorex CD/DVD markers. The regular type's marks had very low opacity (i.e. not dark enough) and really looked quite bad. These new ones don't have that problem - they are dark like Sharpies!
It's been shown that alcohol-based Sharpies really aren't a problem in terms of being safe for use with quality CDRs, but for people who want to be extra-cautious, I think these "metallic" markers are a good option.