imitate

https://www.youtube.com/results?q=imitate

Factor

http://www.actorfactor.net/

Audition

https://en.wikipedia.org/wiki/Audition

Ace
http://www.ace-your-audition.com/

Free
http://www.auditionsfree.com/

Finder
https://www.auditionfinder.com/

Learning the Principles of Acting

http://www.abwag.com/