This year is not only the 30th anniversary of the Back to the Future franchise franchise as a whole, but is also the year in which Back to the Future II is is set.
Which technologies that exist in 2015 (at least as prototypes) were correctly predicted by Back to the Future II ?
To clarify, I am looking only for technologies that were not in existence at the time that Back to the Future II was made. (All technologies that appear in Back to the Future II are relevant, regardless of whether they also appear in other works.)