Audio Joiner from 123APPS.
Audio Joiner is a free tool that anyone can use to combine audio clips. Audio Joiner works entirely in your web browser. No registration is required to use the free tool. To use Audio Joiner simply go to the site, upload the MP3s that you want to combine, then click the "join" button. When the clips are joined you'll have a new MP3 to download. Watch my short video to see how easy it is to use Audio Joiner.