Thinking about Leonard Nimoy's bit part in Them! brought to mind William Shatner's starring role in Kingdom of the Spiders, a tarantula-filled 70's-era horror film. Not real scary, really. I remember seeing this on TV and even as petrified of spiders as I was I was able to watch this without difficulty.
It's on youtube broken up into lots of tiny segments. [As of 5/11/2010 it's no longer there.] trailer:
5/11/2010: Horror Movie A Day has a review.
Yesterday I found the video of Nimoy singing about Bilbo, but Nimoy is not the only Star Trek officer who sings. Here are a couple of classic Shatner pieces: