CloudConvert is an online converter that converts your files in the cloud. Currently it supports over 200 different audio, video, document, ebook, archive, image, spreadsheet and presentation formats like EPS, 3GP or MP4. You can even specify advanced options for every conversion type. CloudConvert is also fully responsive and can be used in all recent mobile browsers. The converted files can be sent to you by e-mail, Dropbox or Google drive which is also a very nice feature.
The free version limits you to a maximum of 1GB filesize and 25 conversion minute per day. The paid packages offer an increased number on both restrictions.