This is an old revision of the document!
http://www.maketecheasier.com/run-android-4-3-in-virtualbox/
https://forums.virtualbox.org/viewtopic.php?f=6&t=58608
http://www.howtogeek.com/164570/how-to-install-android-in-virtualbox/
http://guysoft.wordpress.com/2013/01/05/androvm/
http://forum.xda-developers.com/showthread.php?t=2333452
https://cloud.genymotion.com/page/launchpad/download/
http://blog.zeezonline.com/2013/11/install-google-play-on-genymotion-2-0/
For Android 4.3 on Virtual Box 4.3.6, System > Acceleration > Uncheck Enable VT-x/AMD-V otherwise you'll get kernel panics.
Easiest process is to install Virtual Box first, start it up, then install GenyMotion on Windows. GenyMotion requires GLIB 2.15 which is not in CentOS6.5 - it is in Fedora20. But GenyMotion did not work inside a Virtual Box instance of Fedora20 because it needed OpenGL 2.0 drivers (or something like that).