Mostly I have found the answer to this question by using SL search for the for the particular country in question. However there are some landmarks to international communities to be found at the individual international libraries on Info International. I will note here also sites with strong international communities:
France: Gaia http://slurl.com/secondlife/Gaia/128/128/28
There are newbie tutorials in German to be found at: German Tutorial http://slurl.com/secondlife/Samoa/111/155/558
Germany: Berlin Dance Arena http://slurl.com/secondlife/Berlin%20Dance%20Arena/128/128/27 (follow the green dots on your Mini-Map). The Mondlicht Event Club is quite a popular destination, join the 'Mondlicht - Eventclub' group for notices of events and LMs.
[UPDATE 10Dec08] See this post for a list of international SL sites participating in the Community Gateway program: Gateways into Second Life by Glenn Linden