I have added an implementation of the Single Shot Detector Object detection system to my CognitoZoo project.
Please see the following link for details (it's a GitHub project):
CognitoZoo Wiki link
It can recognise the 20 Pascal object categories. It's really quite fun.
I've also got an implementation of Yolo as well in that project. (The Tiny Yolo v2 version)
From playing with both of them, in my experience the SSD VGG 300 detector seems to have better recognition performance than the tiny Yolo version.There are other versions of Yolo which I hope to implement later.
I hope this is of interest.