From Lifehacker:

Have you ever gone to move a piece of furniture across a hardwood floor and heard the horrible scratching sound of the furniture cutting into the wood? It’s not a pleasant sound, but according to DIY blog Apartment Therapy, you can remove those scratches with an iron and a little water.

As with any home repair tip, it’s best to test this one out in a dark corner before trying it on a high traffic area. The process itself is pretty simple: wet the scratch or dent, apply a wet cloth or paper towel over the dent, and then move the iron in a circular motion across the towel for 3-5 minutes. If you do this on a finished hardwood floor you may have to sand up the finish a little bit. It doesn’t work on all finishes, but it’s incredibly handy if you’ve accidentally destroyed a floor trying to rearrange a room by yourself. Hit up the post on Apartment Therapy for a full guide.

How To Fix Dents in Wooden Floors & Furniture (With an Iron!) | Apartment Therapy