Great Grandmaster Cartographer (Or similar title with diff name)
I think most people could guess what this title would stand for:
100% exploration of all available releases – Grandmaster Cartography title for every release.
To have the Grandmaster Cartography titles for Tyria, Cantha, and Elona is a huge accomplishment, as in most cases you have to beat the game in order to achieve the title and you have to have at least outlined every major area in the game.
The only problem with this title is that it would have to be dynamic. As with each new release you would lose the title until you achieved Grandmaster Cartographer of the new release. I'm am sure it wouldn't be too difficult for Anet to do, but it would be a different system to the titles that are in current use. However they could make a new system for dynamic titles and use it for other new titles that are awarded for multiple titles of the same nature, that are added with each release (Protector titles for instance).
It just seems to be a needed new dimension for titles and Cartography is what I do, thus the suggestion for this particular one. Right now KOBD is seen as kind of a big deal, but it will become less and less so as more releases hit the stage and thus more "easy" titles can be accumilated rapidly, so soon KODB will become NBDA (Not a Big Deal at ALL).
This and similar titles would also promote players to take multiple characters and run them through every release, rather than just the one's they are native to.
If you see someone with this title then you know they've seen it all.

Livingston