Read or talk about your favorite SF or Fantasy writer - or both! Or go out and buy a book from those genres! Many people think they have not read Science Fiction or Fantasy, but when you mention the following books, they suddenly realise - yes, we DO read them:
Angels & Demons by Dan Brown (what, you think we can really contain that much anti-matter for real?)
Fahrenheit 451 by Ray Bradbury
Any of the Harry Potter books by JK Rowling
The Yiddish Policemen's Union by Columbia native Michael Chabon (Alternate History is a mainstay of SFF)
Pride and Prejudice and Zombies by Jane Austen and Seth Grahame-Smith
See? You can find something amongst the classics or amongst the recent bestsellers...
Edited to add - Sharon Lee started this wonderful campaign - here's her announcement.