OPD Editor Guidelines
Cool Sites - Some sites are at the top of the category and highlighted with a star. These are sites picked being more significant in that category. For more
information see the ODP guidelines on Cool
The use of "Cooling" will vary depending on category and subject area. For example, it is used a lot in the Arts categories and almost never used in Shopping. It may be used to highlight a more significant or more reliable source of information. For example, in the case of a performing artist e.g. band, film start, it might be used to highlight the Official Web Site, in order to make it display above fan sites.
For an example of a site [using ODP RDF data] that emphasizes cool sites check out the Cool Directory Project
It can be used for slightly different things, but the general intention is just that it gets listed first in the category. It does not affects rankings, since we don't rank sites. It does not affect how a site shows up in a DMOZ/ODP search since the order or results in a search is almost random. As far as I know no one else pays any attention to it.
It is prohibited for any editor to have his own sites cooled.