of course an issue we'd have is how to not show that extra webpart in the English versions of the page
</br>
</br>we can do that via Javascript (checking with a regular expression the current language from the /lng/xx_XX part of the URL or codebehind logic, but it would be nice if there was also some tag to include or skip parts of the page it wraps based on the current language

e.g. something like

<monox:include language="en_US">

...some webparts etc. markup here...

</monox:include>

and

<monox:exclude language="en_US">

...some webparts etc. markup here...

</monox:exclude>
</br>
</br>in fact such tags could support more (optional) parameters than "language", e.g. a general "test" parameter (check true/false based on some inline evaluation expression one can calculate using ASP.net markup syntax), and other specific parameters regarding page/user state (e.g. "loggedin"). If more than one of those parameters are given, they could be evaluated with an AND (and have some other optional param maybe to override this and evaluate with "OR", "XOR" etc.).

not sure if such a system already exists in ASP.net (like in JSP where there are tag extensions that allow to include a markup based on a condition)

I ended up using Transifex Live, much easier to do localization when you have mixed content in various languages

It seems easy to set it and use, but please note that you do not have control anymore under the localization text because it depends on the Transifex Live.

Regards.