"Macrophilia" refers to a sexual fantasy involving domination by giants, primarily giant women. Variants include metamorphic fantasies; the shrinking of men/women so that average-sized people appear relatively huge, or more commonly, ordinary humans growing to giant size. - http://en.wikipedia.org/wiki/Macrophilia
Macrophilia pops up in various places in today's world I.E. Lee Jeans ad "Don't Flinch" featured a 90 foot super model, the ad can be seen here http://www.YouTube.com/watch?v=DLXb7zhJycc
Seeing as macrophilia is a fantasy it's most active venue is of course, the internet.
Websites such as youtube host videos under the topic of macrophilia and forums with image galleries and chat rooms have member lists that number in the 100,000's