Basically, instead of spamming the forums, it's a place where we allow DaniWeb visitors to feature their websites in exchange for linking back to DaniWeb somewhere on their sites.
The benefits to the people who submit their sites are that their sites get a dedicated page in the directory, are searchable via the sidebar, and the sites they submit are also featured in their member profiles. (So you can go into someone's member profile and see mini screenshots of all of their websites). Another benefit is that the more traffic they send us, the higher we list them in the directory, so they're encouraged to spread the word about DaniWeb on their sites. The top sites that link to us in each category get featured on our main category pages (the mini-screenshots near the bottom).
The advantage to other people is that all of the links in the directory are IT-related, so it's another place to find additional resources on topics of interest ... plus all of the sites are owned by DaniWeb people, so it's an additional community-oriented benefit.