I agree with Guy. The Spanking Tube is a good place to start and see many of the best production companies show their wares. Some of the best producers are:
Nu West/Leda
Realspankings
All of the Claire Fonda sites
Blue Moon Productions
FetishVids
Girls Boarding School
Bars & Stripes
Northern Spanking
Spanking Machine.com
This is just a few of the best. There are only about 2 dozen or so good producers and a few small fry. If it's Femdom stuff you will have to ask someone else as I know a few but don't usually swing that way. Be aware that you can buy clips from many of the good ones on Clips4Sale.com and other reseller sites.
