Oddcast [audiovisual] or here Vocalware [audio only]
Text2VoiceOver [Chrome only]
Google [multi-language, multi=engine] (scroll down and replace the text that appears under "Text to speak" with your own text
ModelTalker (downloads a .wav file)
While there are many downloadable tools one could install to do TTS, for this class homework, we can only accept TTS systems that can be used online (i.e. without any app downloading or installation requirements).