I'd assumed we were talking of things you set up and leave, but if the Dom is in the picture: a simple but fun arrangement, with a woman spreadeagled on the bed, is to shove a hot water bottle under her butt before you start in on her. (None of those fluffy protective covers, just scalding hot rubber.) She will push up against you with real enthusiasm, as well as yelping enjoyably when you thrust hard.
evilll!!!!!!!!
myri {SN} owned by SirNeedles sweet little innocent kitten