Something that allows you to lick any part of the subject, including options on the like french kiss, simple lips licking, teeth licking, simple vag licking, tongue fuck, etc. 

To add to someone else's excellent sheath docking suggestion, I'd like the option to finger sheaths before subjects are fully aroused.

Udder embellishments that can leak/squirt milk uppon orgasm.

Y'know like you can drizzle syrup on the subjects body parts or use a hotdog as a dildo and stuff. Kinda weird I guess.

nipple/clit clamps and/or the ability to pinch

Ever wanted to oil massage a body for foreplay? Spank and squeeze a pair of ass cheeks till you leave a hand shaped red mark behind? Or spread those cheeks open and stretch the asshole with your fingers? Nah? Well, hopefully now you do ;)

Also, foot play could use some time in the sun on Rack 2. A lot more weirdo foot folk (like myself) are finding their awakening nowadays, as evidenced by the Pornhub's most searched suggestions. Maybe not as high up there as "BBC Creams My Wife" or "I Fuck My NOTSister(REAL)", but its pretty popular.