For hard-to-find DVDs:
Robert's Hard To Find Videos in Saskatoon:  www.robertsvideos.com

For general info on who's in what: 
Internet Movie Data Base:  www.imdb.com

For what's on DVD that's on TV: 
www.tvshowsondvd.com

For a look at what's new on DVD: 
www.comingsoon.net