SpeakIt

Select any text on a web page and SpeakIt will read the snippet for you in a not-very robotic voice.

SpeechIt can automatically detect the language of the selected text and can convert text to speech for nearly 50 languages.

Internally, it uses the Chrome Text-to-Speech API (TTS) for speech synthesis and users can change the voice pitch and speaking rate (words per minute).

There’s however no option to download the audio files.