From YouTube: A Boeing 747 being struck by lightning. It's been circulating around for a while, but it's new to me, and apparently it's real. (No reason to doubt it's not.)
I haven't been able to find out exactly where and when this video was taken, but some versions of the video on YouTube state that it was an All Nippon Airways (ANA) flight leaving Osaka, Japan.
Update: Accipiter tracked down some info about this video (see the comments). The plane was taking off from Kamatzu Air Force Base on the coast of the Sea of Japan during the winter sometime before 2003. According to the article Accipiter found, this video helped to demonstrate to researchers that "the vast majority of lightning strikes to aircraft are initiated by the aircraft, as opposed to the aircraft’s intercepting a discharge already in progress."