Overstock has the popular 1" Memory Foam Mattress Topper for $37.99 after this new 5% off coupon (there is also an 7% off coupon for new customers) valid through 10/31. The memory foam is a gel-like substance that adjusts to the warmth and shape of your body, making your bed more comfortable. The 1" size is the most affordable (everything from 1" to 4" is available). Over 1,000 Overstock users rate this 4.5 out of 5, with 93% recommending it to a friend. Shipping is $2.95 and there is no sales tax (except UT, IN).