Insulate your basement with foam board. NEVER use fiberglass. Includes information on insulating floors, too.
Under Floor Insulation
cabin floor insulation
Glass Bottle Floor Insulation
How to Insulate Floors - How to Insulate a House: Tips and Guidelines
Dricore subfloor - perfect for a subfloor for basements.
Finishing a Basement: Walls, Ceiling & Flooring (includes idea on insulation)
wooden floor insulation
FIX MOBILE HOME FLOOR INSULATION - YouTube
Mobile home floor insulation makes a big difference in energy costs and comfort in cold climates. Your best opportunity for mobile home energy savings may be to add more insulation to the roof and floor.Read more...