Leonard Nimoy mixed a little humor into his albums deliberately, but he was serious about his singing voice. He put out a surprising number of LPs. I have the Varese CD of Mr. Spock's Music
that has bonus tracks from The Two Sides
While this material is worlds away from Shatner's album, it too is quite good. The instrumentals have to be taken as very '60s vintage, very hipster, rather than very dated, but give him that and you're off and running.
For more info on all of Leonard's Albums please visit http://www.chaseclub.com/records.html
He recorded more albums than the Beatles you know...