Eyespot

Eyespot aims to be to video editing what Writely is to word processing: a free online tool that replaces expensive software. Still in beta, Eyespot allows you to upload, trim, arrange and output simple video projects.

I haven't tried it, because I'm never far from my laptop. But I can see it being very useful for someone on vacation who wants to edit some quick-n-dirty footage and send it home to Grandma... or for someone who has just shot some amazing footage of his roomate passed out drunk with a penis drawn on his cheek and wants to polish it before emailing it to everyone they know.