No power in the center of the room

You could also put a ceiling light and run cord along ceiling and down to wall with wire casing, found at most home improvement stores, and plug it in to the wall

okay read this quick before it disappears.....there are several styles of cord covers ...some at office supply stores and big box diy places. See what best fits your need

Place a small rug over the middle of the cord, being careful not to cover the ends.

Oh Crystal Ball..... - that every room could have power in the centre of the floorspace, would be a decorator's dream.

I have yet to discover any ideas involving extension chords that are truly safe, or those that do not involve construction and a new electrical plug with a cover on it, installed into the flooring.

Linnet's suggestion would be ok in a very low traffic area, but most electricians do suggest this because it could be a fire hazard. What kind of floor covering do you have and approximately how big is the room?

Use a light on the ceiling. I have a 'rail' with three 'bullet' lights, and the electric outlet is up there. It is a special outlet with the control that sits by my chair, a simple button, push on, push off. I think they are available at home depot. The hard part is getting the outlet in the ceiling. I knew that is what I was going to do, so had it put in during a remodel. Works perfectly.