I usually put in a video for the children while I nurse the baby, prepare a meal, or need a few minutes of peace and quiet.  We do not have cable  so the only kid-friendly channel we pick up is PBS (and we watch it, too).

Over the years we have acquired a collection of DVDs that the children (and I) enjoy watching over and over and over again:

For the younger ones: 

Baby Einstein DVDs

Richard Scarry's Busytown DVDs

For the middle ones:

Madeline DVDs

Looney Toons classic collection

3-2-1 Penguins

The Adventures of Larry Boy

Adventures in Odyssey

For the older ones:

Flushed Away (NEW!)

Toy Story 1 and 2

Finding Nemo

Spy Kids (1,2, and 3)

The Incredibles