I think what he means is to have separate databases and have Links administer all of them from the one control panel. If you have a site or several sites that cover multiple subjects you could have different databases for each subject area and have links run a directory for each one, e.g.; autos, travel, b2b, education, etc.
I appreciate that all the sites/directories would need to be on the same server, but in principle its not such a bad idea. At present you'd need a copy of the entire Links application for each of these subject areas, whereas if you could split them into different databases and publish them to different parts of your site, or different sites entirely, you'd then be able to maintian them all from one point.
You'd also be able to choose which subject you review sites for, since at present, all the categories are mixed together and the sites appear in the validation section by order of when they were submitted, so if you want to review sites just for 'autos' you wouldn't be able to, since the other categories are all mixed in with it and you'd need to review them first before the auto's ones get brought to the top of the list.
I'm sure it wouldn't be a simple thing to do, or whether it would be worth all the effort required to re-write links to manage databases in this way, but I suppose that's why he was asking
All the best
Shaun