Multilingual Support in TYPO3
TYPO3 has multilingual support built right in, no extra extension required. There is a bit of configuration to do, but support for multiple languages is included.
The language support handles in-place switching, meaning that if you are on a page and you select a different language the content of the page changes, so you're looking at the same page, just in a different language (rather than being directed back to the home page).
There are options available for default text and what to do with pages or content which may not be available in all languages
Example sites (these are just two language sites, but many languages can be made available on a single site):