I'm waiting for the easily reversible clip on vasectomy that is in development. Less surgery, and then later you can be like "Hey, I want a kid now" and flip the switch back on easier and again with less surgery.
Like a water valve. http://www.newscientist.com/article/dn13232-sperm-tap-planned-for-reversible-vasectomy.html?feedId=tech_rss20