Yahoo started with two students pooling their lists of favourite links. Then as the list grew ever longer, it made sense to divide it into categories, and then into subcategories. A directory was born. The Open Directory began by inviting anyone and everyone to contribute their favourite links. Since then much agonising and hard work has gone into organising the ever-growing mass of links and providing them with helpful descriptions.
That first stage of gathering favourite sites is easy. Millions of people do it all the time. No wonder that even the simplest website is likely to have a page with a list of links. Some sites have nothing else. Is such a page worth listing? It would add another click for the user between the Open Directory and sites with content. We aim to link directly to sites with unique content. So staff advice is to 'mine' a links page -- extract the links from it for listing in the ODP, rather than list the links page itself.
The ODP does list directories, but we can and should be selective. How useful are they? Do they offer anything unique? The links themselves are not original, so to be worth listing, a directory should provide value to the user in its categorisation, descriptions, and ease of navigation. It should be fresh and well-maintained. Otherwise it will rapidly become full of dead links -- frustrating and useless. If we already have several directories listed on a particular topic it is hard for a new one to add value to the category. We are not obliged to list every site submitted.
There is no need at all to list deep links of directories. Looksmart or Yahoo may well have a category similar to one that you maintain for the ODP. Instead of creating a link to that category, why not search it for useful links? (Naturally, you would need to write your own descriptions.)
Given that the ODP itself is a directory, any directory we list should be significantly different from our own content. More and more we are seeing directories submitted that contain our own data, with or without acknowledgement. Be on your guard! Sometimes such a directory is split into a quantity of subsites on different domains. The site design may be very different from that of the ODP. But don't be fooled.