The first ten films--DVD (second release special editions). (Will be getting them in the two Blu-ray boxes--accidentally came across my Father's Day gift while doing some spring cleaning--oops).
TOS--S1 HD DVD/DVD combo (in this version, the HD is with the new effects, the DVDs have the original effects--can't toggle like on the Blu-ray), S2-3 on Blu-ray
TOS--Errand of Mercy on VHS; bought it many years ago to use in a class as an example of pop culture reflecting contemporary concerns.
every episode of every Trek series, but I've not felt compelled to buy them all. Guess I should turn in my fan credentials.