Awhile back I linked to Media-Convert, a web service that will convert files while you wait. I was duly impressed by Media-Convert, and I'm even more impressed by Zamzar, a very similar free service with a Web 2.0 touch. It can convert between five image formats, 14 document formats, 11 audio formats, and nine video formats, and unlike Media-Convert you can convert many files at once, up to 100MB (though you can only do one kind of conversion at once). After you've selected a file or files to convert, Zamzar will tell you which formats are available to convert to. Then you supply your e-mail address and click "convert" and Zamzar will e-mail you a link to the converted file. Not only was I impressed with Zamzar's ease of use, I was very impressed by its speed. After clicking on "Convert," I received the e-mail instantaneously. Also, the conversion is pretty faithful--though converting a complex Excel file to HTML didn't result in a perfect facimile, it didn't look bad at all. Zamzar is definitely a tool I'll be keeping on hand for when I need to do a quick conversion.