Some great TV shows have made their way onto DVD this week including: Supernatural: Season 6 - a wildly uneven run of episodes but there are still some really solid episodes served up this year, and the high points are just about as strong as anything the show has ever hammered out; The Big Bang Theory: The Complete Fourth Season - there are a lot of laughs in this season and the show is still worth watching; and Mike Hammer - The Complete Series - a pretty good series made even better by its irreplaceable star, Darren McGavin. Other shows recently reviewed include:  Judge John Deed - Season Four, American Experience: Houdini, and The Incredible Journey of Doctor Meg Laurel.  Want more?  Check out all of the TV on DVD reviews in the DVDTalk database.