Exclusive TV previews for Spider-man and Pirates

Two of the summer's most anticipated movies are being promoted on TV before their big-screen debuts. An exclusive preview of "Spider-Man 3" aired during NBC's "Heroes" this week. A commercial also invited Spidey fans to catch more than seven minutes of never-before-seen film footage on the NBC Web site.

The trailer for "Pirates of the Caribbean: At World's End" will make its worldwide debut during the "Dancing with the Stars" season premiere on March 19 - and simultaneously on popular shows in 61 other countries.