It's not all "Find the Mint!"
If you have an anime DVD with really unmissable extra content, please post about it here. Too often, you get only clean openings/closings, trailers, and maybe a commentary or picture gallery. It's easy to miss extra episodes or other valuable entertainment if you're not expecting it.
The best DVD extras I've found so far:
Comic Party--Each DVD has a part of a special hot springs episode.
Utawarerumono--Serious as this series is, Disc 1 has a funny short in the extras.
The Gokusen--the dubbing outtakes are seriously funny!
Fruits Basket--Easter eggs--Funny dubbing outtakes and original screen tests, plus the English version of the song 'Serenade." To find them, go to the Extras menu of Discs 1 and 3, and enter 10 on the remote.