There are some accounts (such as piman's RDF syncs, and my new KT syncs) that aren't really LiveJournal-related, but are also services that are provided to the LiveJournal community.
Other projects (like the "userpics" community) could also belong to this account type.
The privileges could even be identical to a free account... but it'd be nice to be able to edit the style. In any case, switching the account type on something like "kt_linux" gives it that extra bit of LiveJournal blessing it needs to feel official. :)