I've been reading a motivational book written in the 60's ( Success Through A Positve Mental Attitude ), and the author uses the expression "many a" quite a few times.

Is this expression still in use nowadays? I saw in the dictionary that it is an adjective ( a modifier ) but I'm not sure if I can still use it in Standard American English.

Are the forms below correct?

many a + singular noun 

many a + plural noun

Would you write a few usage examples?

Thanks for your help!