Now that we've all established ourselves as incurable Star Trek geeks, I'd like to add that I did some considerable research over the years and found the offset filming locations used in the original Star Trek series. If anyone is, or planning on, being in the Los Angeles area and would like to "boldly go where no man has gone before" then simply email me (s66[at]smrn[dot]com) and I'll send you the basic details via an MS Word document. I used both DVD playback and a GPS to log a few specific scene locations. I think I'm the only trekkie who ever compiled this information and I had a lot of fun finding these places.
I even discovered some odd trivia along the way, like the obelisk (asteroid deflector) in "The Paradise Syndrome" was the exact same location where Andy and Opie were skipping stones in the beginning of "The Andy Griffifth Show", or the back side of the Bat Cave was used as the slaves' hideout in "Bread and Circuses".
Here's a sample picture: Vasquez Rocks in Agua Dulce. The fire department on the right is watching a helicopter rescue while some filming group on the left is making their own Trek episode.