If you could have a means of contraception, safer sex, or both, that don't (yet!) exist, what would they be?
I'd really have always just liked a simple on/off switch for my uterus, when it comes to babymaking, myself. You want the babies, you turn it on. You don't, you shut it off, without having any of the effects something like a hysterectomy has, or the cost or invasiveness of a tubal or IUD.
Also, I'd love it if there were a condom that basically was attached, at the base, to a dental dam. Not only would it likely reduce everyone's HPV and genital herpes rates down to almost nothing if people used it, you'd basically have something that was about as multi-use, all in one little package, as it gets!
Oh! And lubricant that self-adjusted its consistency to what you needed it to be. In other words, if what you were doing really required something thicker, it'd go thicker. If you were already pretty self-lubricated, it'd stay thin and spare unless that changed.