One of my fetishes has already been mentioned which is a lady using her strap-on on me. Something else I would love to do would be CFNM, I would like to serve as a naked waiter to a group of sexy young ladies at a tea party or such like.
Some examples of what I'm thinking
http://www.twistedteas.org/
http://www.geocities.ws/cfnm_party_house/