Uses

Interactive Menus:
http://www.youtube.com/watch?v=vkAxOh3nIDY

Interactive menus are used mostly on DVD's to navigate through special features, play the film or choose a certain scene or episode
Animated Captions:
http://www.youtube.com/watch?v=7EWd3Ryi4a4

Idents:
http://www.youtube.com/watch?v=8o0xOW4umuI

Idents are used on Channels to promote that specific channel and or company and are often Shown before a Film or Tv show begins
Title and Credit Sequences:
http://www.youtube.com/watch?v=sY4f_83t_rw

Title and Credit Sequences are at the start or end of a film when people and companies are credited for their work on the film
Stings:
http://www.youtube.com/watch?v=OIEa622K8ow

A sting is very similair to an ident but is often more creative and  certain channels like E4 Hold competitions for peopel to create stings to show off their creative flair and technical skill

Web banners: