Nanites.
I always wish for Nanites.
Or, if the genie was too weak to deliver on Nanite technology, then I'd like to (at will) have mental holographic pop-ups appear over people's heads indicating their current sexual orientation, relationship status, threat level (ie, nice person to axe murderer), the presence of STDs, and how attractive they find me on a scale of 1 to 10. And possibly one or two other items (like interest levels in casual sex or polyamory) The "at will" bit meaning that I could turn the power on and off rather than having it all the time.
So yeah, basically the cheat codes to figuring out who would be up for casual sex/poly relationships.
Edit: Oh! Or, if that was too complex, then the ability to talk to cats. I really wish I could explain to my cat that she gets fed as specific times of day, not simply by my strange human whim.