What is the closest we’ve gotten to simulating a human in a computer?
The Loebner Prize Turing test has become highly controversial; however, Bruce Wilcox‘ ChatScript engine has won quite a few times already, including again in 2015 (for details see brilligunderstanding.com)
IMHO, the University of Southern California (USC) Institute for Creative Technologies (ICT) Virtual Human Toolkit (vhtoolkit.ict.usc.edu) is likely the best general purpose tool; however, it is only available to bona fide researchers, or those with very deep pockets.
One of the most interesting projects of this kind to receive a lot of attention in the media in the recent past is the University of Auckland New Zealand, Auckland Bioengineering Institute, Laboratory for Animate Technologies BabyX, directed by associate professorMark Sagar.