Assistive Technologies on Chrome OS by WebApps (SaaS) or extensions

Hi everyone,

Do you know good A.T. (Assistive Technologies) we can use on Chrome OS
as Screen reader or Voice browser, webapp (offline options if possible) or
extensions in chrome. (This solutions can be used in all of Operating
System because of webapp format.) ?

You know ChromeVox (extension or native in chromeOS). but chromevox have a
bug in tables elements : he doesn't read correctly (associatives cells).

Thanks for all !
Best regards,
Ludo,