TV.com is good, and is better then IMDB alot of the times.
The best place for Television is http://thetvdb.com/
very nice site, with really good pictures for TV series and the info is the best out there that ive come across.
They have Banners, Cover art, Cast pictures, Fan art and each episode usally has a picture from the episode, along with the info that you can download through there XML APIs. I just cant figure out how to get that stuff to download over to movienizer, without having to manually do it all.
It would be awesome to have that site added to movienizer.