Typically, when we speak of 'ranked' peaks, we're ranking by height using a minimum prominence threshold. However, there is another way to view such a list: it is also a list of the most prominent peaks in a region.
For example, instead of saying that John has ranked the 62,000 P300's in the west by height, we could also see it as a list of the 62,000 most prominent peaks(points) in the west.
Mike is right that the lists of Utah 12ers, e.g., on the site do endorse a P300' system. Ryan's concept is interesting - let people designate their own prominence cut in the way one can often chose their own time zone. Of course, this could get a bit more complicated if I decide I want different cuts in different states or fancier methods like Al suggests(prominence/height ratios).
Also, if someone wants P200 lists, or to the extreme - lists of every measured elevation and every closed contour, then there is a lot more work that needs to be done!
The English vs metric issue is tough - eventually we have to yield to metric, but it's tough when the maps are mostly English. As discussed before, Bross, Challenger and "Thunder Pyramid" come off the high 100 if we convert from 300' to 100m.