The Brickvention 2011 website (see my links) refers to AFOLs. If you haven't heard of that before, it stands for Adult Fans of LEGO.
There is a good blocumentary by Jess Gibson, featuring several AFOLs.
"Passion combines with creativity in this documentary that features a selection of AFOLs (Adult Fans Of LEGO) from the Pacific NorthWest."
Check it out at this link: http://vimeo.com/9581676