>In Argentina (specifically around Buenos Aires), we don't use the term "tu", but "vos" instead, to call our friends, relatives, or kids. This is quite unique. Thre are very few places in Latinamerica, and some people at Palma de Canarias who use this form. It goes all the way back to an ancient form of the language used indeed as very formal. I really don't know why we keep using this instead of the pervasive "tu".

I noticed, in Argentina, that this for is not only used for friends, but also, a lot, among people who see each other for the first time.

In Bolivia, we use "tú" in the larger part of the country - but in the low lands (Departamentos Santa Cruz, Beni, and, pressumably, Pando, which I haven't visited) they use "vos" instead, amongst friends. For people they don't know, they also use "usted".

I find it strange, but it is a common custom (also in the lowlands) for children to call their parents "usted" - pressumably as a sign of respect.

Hilmar.