1 Hoverboards
We don't have Pitbulls or Mattel hoverboards yet, but Japanese car company Lexus recently unveiled a prototype for a real, rideable hoverboard. A company called Arx Pax in California is also working on its own version, with help from a Kickstarter campaign. Unfortunately they both rely on magnets, so are unlikely to be able to fly over water like Marty's.
2 Wearable technology
In Back to the Future II, Marty's future kids wear headsets at the dinner table to make and receive calls and watch TV. With the introduction of Google Glass in 2013, and gaming headsets like Oculus Rift in the works, virtual reality is not far off, and Microsoft's recently announced Hololens bears more than a passing resemblance to Junior's goggles.