Aside from Big Brother, they generally put out some quality shows. Some of my favourites (I had to go through their site, they have done so many),

Bo Selecta
The Ali G show
Scrapheap Challenge
Black Books
Father Ted
How clean is your House?
The IT crowd
Peep Show
Trigger Happy TV
Unreported World
Vic Reeves Big Night Out
Wife Swap (Awful, but compulsive)

Ok, they're mostly comedies, they also produce numerous in depth documentaries, too many to list.

I'll always remember them as a young boy for showing the more racy films and borderline soft porn, handily identified with a little red triangle in the tv guide.