Real Estate Investment Clubs are associations that focus on education and networking, often hosting for- profit seminars, books, tapes and investing services. Some clubs are actually for-profit businesses, often founded by a real estate investor with some strategy or service to promote.

According to Wikipedia, some Real Estate Investment Clubs pool their financial resources in order to make real estate investments.

The National Real Estate Investors Association represents local investor associations, property owner associations, apartment associations, and landlord associations on a national scale. The NREIA represents the interests of approximately 40,000 members across the U.S..

Sources:
http://articles.moneycentral.msn.com/Investing/RealEstate/RealEstateClubsRideTheHousingBoom.aspx
http://www.nationalreia.com/ClubPortal/ClubStatic.cfm?clubID=795