DMOZ is an open source directory that aims to list all relevant websites on the web in their specific categories. One of the problems with DMOZ is that it is poorely staffed and as a result, getting your site listed can be a pain.

Google used to value DMOZ very highly in the past, but because of the limitations of the directory, it has moved away from DMOZ in recent years. Saying that, a link from DMOZ can still help your rankings quite a bit, but it isn't the 'must get link' that it once was.