Melobytes is described as 'Turn any text into song' and is an website in the Audio & Music category. There are three alternatives to Melobytes, not only websites but also apps for iPad and iPhone. The best alternative is Yarn.co, which is both free and Open Source. Other great sites and apps similar to Melobytes are Comb.io (Free) and Clash.me (Free).
Clash.me lets you assemble soundbites from text input by combining multiple sources. Basically, you enter some text and the web app pulls audio and video snippets from popular sources to create an entertaining mashup.