Currently we have no consistent method of posting things like DVD specials (for example, the Geass picture books), or unreleased episodes released on a DVD (like ep 24 of Clannad). None of the other major anime sites follow this consistently either; anidb tends to never make separate entries for anything released on a DVD along with a TV series, and ANN is wildly inconsistent, sometimes posting new entries and sometimes adding extra episode counts in the main entry.
I posted a thread awhile ago with a proposal for how to deal with this
, but it didn't receive much response. Hopefully now more people are around to give opinions... please read and respond in this thread!