[Javascript] Select Box or Radio which will automatically make more of same

[groups at bluepixelweb.com]

I am looking for a script I saw once which allowed a user to select a choice, either by a select box or radio button, and their selection would make more boxes. 

My example would be: 

"How many dogs do you own?" 
If they choose "3" , by select or radio, then it would make three select boxes (in each box I would have a breed of dog selection). 

Any ideas on how I could find this script again? 

Thank you!