So there's some guy out of California who has invented this Galactic Cap. It is a 2 piece thing that sticks to the head of your dick and then a "cap" goes on the top and traps the semen. Guy also goes on to say it prevents HIV and pregnancy, but not herpes or any of those skin to skin STIs.
http://youtu.be/XVhYD-1_bxs
Would you use this instead of a condom? It supposedly leaves the most sensitive parts of your dick exposed so that its a more natural feeling during sex.