I just want to second the method that Alex suggested on his May 30th post. He suggest wearing pantyhose and Antron Nylon panties and a slip then rubbing on a blanket in bed. I have been doing this for about a year now and it feels great. I will put on a pair of nylon panties and bra and slip. I usually have my cock out the leg rubbing the inside of the slip. The smoothness of the material on my cock is nice and I am soon pumping my load inside the slip.
Another great feeling is wearing a Nylon Lycra Spandex leotard. (sometimes I'll wear it all night). When I'm ready to get off, I leave my cock inside and slowly hump my blanket. Again, the smooth material feels great and I am soon filling the inside of the leotard with my hot cum. The warmth of my cum against my skin makes me cum even harder.