Zamzar is an online file conversion tool that allows you to convert video/audio files, images, text documents without needing to download any software. Simply upload the file you would like to convert, choose the format you want to convert your file to, and type in your email. The Zamzar site will email you with a link that can be used to download your converted file. Popular conversions include PDF to Word, MP4 to MP3, WAV to MP3, DOCX to Word, and JPG to PNG. The free version restricts file uploads to 100MB, but Zamzar also offers premium paid accounts that support larger file sizes, online storage, concurrent conversions and more.
Check it out here: http://www.zamzar.com/