My son is probably the world's biggest Mighty Machines fan! His favorite right now is the recycling one so we watch is over and over
I've learned so much from that show- I never knew how most of these things worked (except for the public transit one which was filmed at my work, working all night and then coming home to watch it on TV gets a little dull!).
My son always amazes people by knowing the correct names for the machines- the other day he was looking at a book and pointed out a combine... we were like "a what?"