There are a number of sites now offering online video conversion. Some work better than others. However, this is the first site I’ve come across that has an impressive array of video conversion formats, as well as document, image, and music formats.
Like many of these online conversion tools, they require an email address to send the file. I’ve set up a spam email account at Google for just this type of service. It works great! But beware that there is a 100MB file size limit.
Check it out: Zamzar