Can you find a mattress pad that can be used on a king size memory foam mattress that COOLS the person sleeping on it?

You should try the Newpoint International Gel Filled Mattress Pad. It is quite comfortable and the gel really cools the person sleeping on it. It should fit the memory foam mattress also.

There are some cool memory foam mattress pads at http://www.overstock.com http://tinyurl.com

Hello Again!
Wow, I didnt know they had full cooling pads, I knew about the pillows , these look really neat, wish they were a bit cheaper!
One design is the ChillPad Mattress Topper which sells for $649.00!
specifics are:
Your best night's sleep is a few degrees away. If you have not yet achieved your perfect night's sleep or if you do not get enough of it, the ChiliPad is the solution. This is the only cooling and heating temperature control system for your bed and is the ideal solution. Cool mattress pads promote better sleep! ChiliPad dual control (Queen and King Size) heated mattress pad quietly heats or cools your bed for a comfortable, restful sleep. Bed too cold? Too hot? ChiliPad makes it feel just right! Now you can safely raise and lower bed temperature to suit your perfect sleeping environment. Order your ChiliPad heated mattress pads today and improve your nights by degrees! Technology ChiliPadT technology uses water instead of air to generate a wide range of in-bed temperature adjustment. Similar to the semi-conductor technology that cools your computer, water passes by the chip and depending on the direction of electron flow the water is cooled or heated. The water flows through soft coils in the mattress pad actively adjusting the temperature of the surface. Using advances in semiconductor technology the temperature can change from 65°F to 100°F, at a fraction of the cost of air-conditioning. The result is the effect of a cool or warm bed throughout a night.s sleep. The motor is virtually silent (under 45 decibels) and has been designed to fit under a standard bed frame. It is controlled in one degree increments with a hand held remote. The benefits of a cooler night.s sleep are medically proven to increase the amount of REM sleep during the night. This is a revolution in sleep!

• Savings to your energy bill. The ChiliPad can be controlled from 68-118F, which will help keep your energy costs down.
• Universal-fit 200-thread-count quilted mattress pad.
• Patented technology that cools and heats the bed - the ChiliPad is an innovative way to regulate the temperature of your bed at night and helps in achieving restful sleep.
• The coiled design creates an equally balanced temperature in the bed to consistently keep you at your desired temperature throughout the night.
• Adjusting the temperature is easy with simplistically designed wireless remote.
• ChiliPad is sold with a 3 year manufacturer's warranty

There is also the Cool Comfort Memory Foam Matress Topper.  The standard King starts at $299 and has free shipping!
specifics are:

The 4 inch CoolComfort Memory Foam Mattress Pad Topper is the thickest they offer,

giving plenty of depth to sink into while enjoying the luxuriously conforming feel of the visco elastic memory foam topper. Unique and revolutionary CoolComfort foam was specifically developed with night time comfort in mind, even if you tend to sleep a bit warm. CoolComfort memory foam has been designed to provide a cooler sleep surface, with the same cradling and conforming qualities that memory foam toppers are known for worldwide.

A much more open and breathing cell structure to the foam --

consistently throughout the memory foam mattress pad topper -- is the key. Research suggests that air flows through the material far more freely than traditional visco-elastic memory foam, helping keep you cooler and dry all night long. In fact, the air flow through CoolComfort can be up to eight times greater than competing brands. Air moving through the foam itself is what carries away excess heat and moisture, creating an exceptionally comfortable sleep experience.
Get luxury sleep with a CoolComfort Memory Foam Mattress Pad, and enjoy the most comfortable and advanced viscoelastic memory foam bed and mattress topper available today! CoolComfort is available in 2", 3" and 4" heights, with an optional 200-count cotton mattress cover, luxuriously quilted with 7 oz of polyfill fiber.'