We recently visited the VLA (Very Large Array) - what a fun trip for the kids! Even the 4 year old really enjoyed the video presentation. He said to me, "Mom, I like radio telescopes."
The kids learned a lot, and it was an experience I'm sure they'll never forget! How perfect that "Contact" is going to be on tv this week!
A great website for using movies to learn about science - Bad Astronomy, by Phil Plait. This is great for older kids to use to evaluate the scientific merits of popular movies.