I don't use the term "mixed" really but it's pretty common (especially among younger people). I just say multiracial.
When we lived in San Francisco, GF and I would get pegged as Asian/CC (especially GF). They weren't really used to having a lot of NA/CC people around, and we have more almond eyes with dark hair and light(ish) skin. So, GF especially looks Asian. A few times we had older people come up to us and start a conversation in Chinese! Very cool.
I'm happy that someone mentioned the 'coloureds' racial classification -- it still exists in many areas and basically means BR/multiracial. In many areas, it's not a racial slur, just how they classify your race. In South Africa, if you weren't CC and you weren't Bantu (AA), you were coloured (BR/MR).